text:
GCSE Science/The motor effect

GCSE Science/Electricity

The motor effect is the term used when a current-carrying wire in the presence of a magnetic field experiences a force. A simple experimental demonstration will show you that this is true.

Place a wire that is connected to a power pack in between the poles of a horseshoe magnet. Turn on the power and the wire moves. Often the movement is only very slight because a typical horseshoe magnet is not very strong.

The force depends on a number of things:
 * How strong the magnetic field is inside the loop of the magnetic coil as it is usually iron and iron is a good conductor of magnetic attraction.(B)
 * How much current is flowing through the wire. (I)
 * The angle formed between the wire and the direction of the magnetic field.(θ)
 * The length of the wire, carrying the current, in the magnetic field.(L)

The force obeys the formula: $$F=IBL\sin(\theta)$$

The first two points are pretty much obvious, so let's look at the third point in a little more detail. The magnetic field of a horseshoe magnet points pretty much in a straight line from the north pole to the south pole. If the wire cuts this field at right angles the resulting force will be a maximum. If the wire runs parallel to the field, from the north the south pole or vice versa, the wire will still experience the motor effect. However, the net result of this force is along the wire, not perpendicular to it, thus the wire does not turn.

Having said that, at GCSE you only really need to think about situations where the field and the wire cut each other at right angles. The force is always at right angles to both the field and the current flowing in the wire. This means that if you draw the direction of the magnetic field and the wire on a piece of paper the force will be out of the plane of the paper pointing straight up or down {More about how you work out which way later).

Look at the diagram above. For simplicity, only the two ends of the horseshoe magnet have been drawn. Also the power pack and connecting wires are not shown either. The magnetic field is going into the screen. The current is traveling from right to left. The black line represents the force, and therefore the direction that the wire moves.

 * Q1) Name one way that the force on the wire could be increased.
 * Q2) Name as many ways as you can to reduce the force on the wire.
 * Q3) Name two ways of reversing the force on the wire, so that it pushes the wire up rather than down.

Fleming's Left Hand Rule

This rule allows you to work out which direction the force will point in. Arrange your left hand with your thumb, first finger, and second fingers all pointing at right angles to one another.

 * Point your F irst finger in the direction of the magnetic  field.
 * Point your Se C ond finger in the direction of the current.
 * The Th umb will then give you the direction of the force ( thrust ).

Remember you have to use your left hand for this! Although you may use your right hand so long as you swap the direction of current with the force

Q4) A student uses her right hand instead of her left. What effect will that have on the force she works out?

You will recall that a current carrying wire is surrounded by its own magnetic field. The diagram below shows the wire end on in a magnetic field of two magnets that are NS facing. The field due to the magnets is shown in blue, and the field due to the current in the wire is shown in black.

Notice the direction of the two fields as shown by the arrows. On top of the wire the fields are both going in the same direction. They add up making an overall strong field.

Underneath the wire, they go in opposite directions. They cancel each other out to some extent making an overall weaker field. The new field is shown in the diagram below.

See how the field above the wire is stronger. The lines are closer together. Below the wire the field is weaker (due to partial canceling out) the field lines are further apart. The force pushes the wire downwards, away from the strong field into the weak field. It's as if the field lines try to repel each other. They don't like being squashed together and try to straighten out. They also act as if they are made of elastic bands, they don't like being stretched out of shape. (This is just a model of what's going on. The lines aren't real, they don't actually try to push each other away, but I find it a way of helping me understand what's going on. If it doesn't help you, don't use it)

 * Q5) Use the idea of field lines not liking being squashed together to explain why two magnets with like poles facing each other repel.
 * (Q6) Use the idea of field lines being made of elastic to explain why two magnets with opposite poles facing attract one another.

A simple electric motor
Ok, so far we have been looking at the force that results when we put a current carrying wire in a magnetic field. In this section we will look at a practical use for this force.As you have probably already guessed from the name of this page, the practical use is going to be an electric motor.

Look at the diagram above. A rectangular loop of wire is sitting inside a magnetic field. We can consider the current in the four sections of the loop and work out which way the force acts.
 * On the left hand side of the loop the current is flowing into the page or screen. The magnetic field will be going from left to right so from Flemming's left hand rule the force will be downwards.
 * On the back and front of the loops the current is parallel to the magnetic field so there is zero force.
 * On the right hand side of the loop the current is coming out of the page or screen. The field is still going from left to right so the force will be upwards.

The net result of these different forces is that there will be a turning moment that makes the coil rotate by 90°. At that point the upwards and downwards forces will be acting along the same line and the coil will stop turning. Another way to think about it is to consider the loop as a tiny little one turn solenoid. The solenoid will have a little north pole and a little south pole and will therefore move until its north pole lines up with the south pole of the magnet on the right, and its south pole lines up with the north pole of magnet on the left.

This is all very interesting but not much use as a motor. We want something that keeps turning all the time the current flows. They way this is achieved is by the use of the commutator – a circular metal ring that is split into two halves. The ends of the wire loop turn around inside the commutator. They are in electrical contact with it. One side of the commutator is connected to the positive output of a power pack or battery. the other half of the commutator is connected to the negative.

Let's look at what happens as the coil turns inside the commutator:
 * 1) The coil turns clockwise because of the forces on the two halves as explained above.
 * 2) As the coil turns the wires slip around on the inside of the commutator.
 * 3) When the coil is in a vertical position there is no force on it, but its momentum carries it forward a little.
 * 4) The wires inside the commutator make contact with the other half of the ring. I.e. the wire that was in contact with the positive half of the commutator now touches the negative half and vice versa.
 * 5) This causes the current to flow the other way around the coil, which reverses the little solenoid magnet.
 * 6) The coil therefore tries to line itself up with the magnetic field by continuing to turn so that it ultimately points in the other direction.
 * 7) Once the coil is vertical, and facing the other way, the wires touch their original halves of the commutator. and the whole cycle repeats over and over

Q7)A student sets up an electric motor and turns it on. The coil turns clockwise. List two ways she could reverse the direction.

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title: GCSE Science/The motor effect


text:
C Programming/Advanced data types

In the chapter Variables we looked at the primitive data types. However advanced data types allow us greater flexibility in managing data in our program.

Structs
Structs are data types made of variables of other data types (possibly including other structs). They are used to group pieces of information into meaningful units, and also permit some constructs not possible otherwise. The variables declared in a struct are called "members". One defines a struct using the  keyword. For example:

is a variable of type, which we declared along with the definition of the new   data type. More commonly, struct variables are declared after the definition of the struct, using the form:

It is often common practice to make a type synonym so we don't have to type "struct mystruct" all the time. C allows us the possibility to do so using a  statement, which aliases a type:

The  itself is an incomplete type (by the absence of a name on the first line), but it is aliased as. Then the following may be used:

The members of a struct variable may be accessed using the member access operator  (a dot) or the indirect member access operator   (an arrow) if the struct variable is a pointer:

(Pointers will be explained in the next chapter.) Structs may contain not only their own variables but may also contain variables pointing to other structs. This allows a recursive definition, which is very powerful when used with pointers:

This is an implementation of the linked list data structure. Each node (a restaurant order) is pointing to one other node. The linked list is terminated on the last node (in our example, this would be the last order) whose  variable would be assigned to.

A recursive struct definition can be tricky when used with. It is not possible to declare a struct variable inside its own type by using its aliased definition, since the aliased definition by  does not exist before the   statement is evaluated:

The size of a struct type is at least the sum of the sizes of all its members. But a compiler is free to insert padding bytes between the struct members to align the members to certain constraints. For example, a struct containing of a char and a float will occupy 8 bytes on many 32bit architectures.

Unions
The definition of a union is similar to that of a struct. The difference between the two is that in a struct, the members occupy different areas of memory, but in a union, the members occupy the same area of memory. Thus, in the following type, for example:

The programmer can access either  or , but not both at the same time. Since  and   occupy the same area of memory, modifying one modifies the value of the other, sometimes in unpredictable ways. This is also the main reason that unions are rarely seen in practice.

The size of a union is the size of its largest member.

Enumerations
Enumerations are artificial data types representing associations between labels and integers. Unlike structs or unions, they are not composed of other data types. An example declaration:

In the example above, red equals 0, orange equals 1, ... and so on. It is possible to assign values to labels within the integer range, but they must be a literal.

Similar declaration syntax that applies for structs and unions also applies for enums. Also, one normally doesn't need to be concerned with the integers that labels represent:

This peculiar property makes enums especially convenient in switch-case statements:

Enums are a simplified way to emulate associative arrays in C.

de:C-Programmierung: Komplexe Datentypen Programmation C/Types avancés C/Typy złożone

license: Creative Commons - Attribution Share-Alike - https://creativecommons.org/licenses/by-sa/4.0/

title: C Programming/Advanced data types


text:
Physics Study Guide/Logs

=Review of logs= Been a while since you used logs? Here is a quick refresher for you.

The log (short for logarithm) of a number N is the exponent used to raise a certain "base" number B to get N. In short, $$\log_B\ N = x$$ means that $$B^x = N$$.

Typically, logs use base 10. An increase of "1" in a base 10 log is equivalent to an increase by a power of 10 in normal notation. In logs, "3" is 100 times the size of "1". If the log is written without an explicit base, 10 is (usually) implied.

Another common base for logs is the trancendental number $$e$$, which is approximately 2.7182818.... Since $$\frac{d}{dx} e^x = e^x$$, these can be more convenient than $$\log_{10}$$. Often, the notation $$\ln\ x$$ is used instead of $$\log_e\ x$$.

The following properties of logs are true regardless of whether the base is 10, $$e$$, or some other number.

Adding the log of A to the log of B will give the same result as taking the log of the product A times B. Subtracting the log of B from the log of A will give the same result as taking the log of the quotient A divided by B. The log of (A to the Bth power) is equal to the product (B times the log of A). A few examples: log(2) + log(3) = log(6) log(30) – log(2) = log(15) log(8) = log(23) = 3log(2)

title: Physics Study Guide/Logs


text:
Physics Study Guide/Electricity

=Electricity=

The force resulting from two nearby charges is equal to k times charge one times charge two divided by the square of the distance between the charges. This what force of attraction between to charged particle says, according to coulomb's law.

The electric field created by a charge is equal to the force generated divided by the charge.

Electric field is equal to a constant,  “k”,  times the charge divided by the square of the distance between the charge and the point in question.

Electric potential energy is equal to a constant,  “k”  multiplied by the two charges and divided by the distance between the charges.

Variables

Electricity acts as if all matter were divided into four categories:

 * 1) Superconductors, which allow current to flow with no resistance. (However these have only been produced in relatively extreme laboratory conditions, such as at temperatures approaching absolute zero)
 * 2) Conductors, which allow electric current to flow with little resistance.
 * 3) Semiconductors, which allow some electric current to flow but with significant resistance.
 * 4) Insulators, which do not allow electric current to flow.

Charges are positive (+) or negative (-). Any two like charges repel each other, and opposite charges attract each other.

Electric fields
A charge in an electrical field feels a force. The charge is not a vector, but force is a vector, and so is the electric field. If a charge is positive, then force and the electric field point in the same direction. If the charge is negative, then the electric field and force vectors point in opposite directions.

A point charge in space causes an electric field. The field is stronger closer to the point and weaker farther away.

Electricity is made of subatomic particles called Electrons and so are Electric Fields and Magnetic Fields. One must also note that electrical fields come under the category of spherical fields as the inverse square law may be applied to the electrical field. This means that the electrical force, exhibited by the electrical field emitted by the subatomic electron charge (-), acting upon a body is inversely proportional to the distance between the center point of the electric field (subatomic electron) and the body on which the electric force is acting upon.

An electric circuit is composed of conducting wires (through which an electric current flows through), a key or switch which is utilized to open and close the circuit, components which transfer electrical energy to a form of energy required by the component and an electromotive source (such as a voltaic cell). A voltaic cell is an electromotive source in which are present two plates, zinc and copper, placed in dilute sulphuric acid. Whence the circuit is closed the zinc reacts with the sulphuric acid to produce zinc sulphate. The electromotive force which discharges the electrical energy in the electric current is considered to be originated on the surface of the zinc plate in the voltaic cell. However, depending upon the cell, closing the circuit gives rise to polarization, accumulation of hydrogen bubbles on the surface of the copper plate which seriously interferes with the movement of electricity and reduces the magnitude of the electromotive force. For this reason Leclanché cells are utilized. Consisting of similar characteristics as that of the voltaic cell however a Mage difference is present. Instead of the use of copper plates, a carbon plate is used. For this reason, magneze dioxide may be placed on the carbon to react to form a compound which whence in contact with hydrogen bubbles will turn the hydrogen into water, hence increasing the size of the electromotive force produced by the cell. The resistance encountered in conducting wires: Inversely proportional to the diameter of the conducting wire. Directly proportional to the length of the conducting wire. Varies with different substances. Varies with temperature of the conducting wire.

In order to maintain a constant flow of an electric current a constant expenditure of chemical or mechanical energy is required. An electric current is accompanied by an electric field and a magnetic field. A device employed into determining the presence of an electric current is known as a galvanoscope. The conducting wire through which the electric current flows through is he led over and parallel to the galvanoscope the magnetoscope preset inside of the galvanoscope being deflected in the opposite direction to which the electric current flows in. So with the aid of a galvanoscope one may not only deduce the magnetic properties of an electric current, the exhibition of a magnetic field, but the direction in which the current flows through. An electromotive force may also be generators by a dynamo. A rotating magnet present inside of a helix. The magnetic properties of electric currents may be used to construct magnets. An electromagnet is commonly described as a mass of iron on which is placed a helix/solenoid through which flows an electric current. The magnetic field emitted by the electric current is increased if the solenoid is placed around a magnetic mass of iron or any other substance possessing magnetic properties, that is the magnetic field of the iron is added to that of the electric current producing a more powerful magnetic field. Conductors may be arranged in two variants. Series and parallel circuits. In series, the current passes through each conductor in turn, where Ohm's law changes to I = nE/(nr + R), where I is the current intensity, n is the number of cells arranged in series in the circuit, E is the electromotive force applied to the circuit, r is the internal resistance ( the resistance the current that is produced in the cell experiences whence passing from the zinc plate to the copper or carbon plate through the sulphuric acid ) and R is the external resistance.

 * For a good introduction to Gauss' Law and Ampere's Law, check out this website

title: Physics Study Guide/Electricity


text:
Lojban/Vocabulary 1

Wordlist

 * doi
 * coi
 * be'e
 * je'e
 * je'enai
 * co'o
 * re'i
 * re'inai
 * zo
 * ma
 * la
 * mi

 * smuni
 * gismu
 * lujvo
 * tanru
 * sumti
 * bridi
 * cmavo
 * cmene

cmavo
doi      DOI      vocative marker generic vocative marker; identifies intended listener; elidable after COI

coi      COI      greetings vocative: greetings/hello

be'e     COI      request to send vocative: request to send/speak

je'e     COI      roger vocative: roger (ack) - negative acknowledge; used to acknowledge offers and thanks

je'enai  COI*     negative acknowledge vocative: roger (ack) - negative acknowledge; I didn't hear you

co'o     COI      partings vocative: partings/good-bye

re'i     COI      ready to receive vocative: ready to receive - not ready to receive

re'inai  COI*     not ready to receive vocative: ready to receive - not ready to receive

zo       ZO       1-word quote quote next word only; quotes a single Lojban word (not a cmavo compound or tanru)

ma       KOhA7    sumti ? pro-sumti: sumti question (what/who/how/why/etc.); appropriately fill in sumti blank

la       LA       that named name descriptor: the one(s) called ... ; takes name or selbri description

mi       KOhA3    me                    pro-sumti: me/we the speaker(s)/author(s); identified by self-vocative

doi
{doi} works like vocatives like {coi}. A speaker or author tells who they want to listen or read after this word. {do} stands for the listener.

In English poetry sometimes people say O before names, but usually people just put the name at the beginning or the end of a sentence separated from the rest by a comma or as a sentence of its own. In English, people also say "Hey" before names. This carries the added effect of getting someone's attention.

If I felt like saying something completely useless, I would say {doi do}, identifying the listener as the person listening.

Can someone say {doi} by itself (without a name following like I can with the rest of the vocatives)?

coi
Near the beginning of a conversation or upon noticing another Lojban speaker to talk to, a Lojban speaker will often say {coi}. The listener usually replies {coi}.

This has about the same meaning as the English words "Hi", "Hello", "Howdy", and "Greetings". As with most of the vocatives, I can follow it with a name. It must either have la or a mandatory pause between {coi} and the name.

A common Lojban phrase {coi ro do} means "Hi, all.".

{coinai} means the opposite of {coi}, and therefore "goodbye", but most people say {co'o} to express that thought.

be'e
A Lojban speaker not speaking, wanting to speak, and not sure if other speakers will allow him/her to speak will sometimes say {be'e} to ask permission.

In English, people usually only ask to speak on formal occasions like the courtroom and in large meetings. In school students raise their hands for a turn to speak. When people say "Excuse me.", they don't expect someone to deny them from speaking. They also ask "May I have a word with you?" Like most vocatives, I can follow {be'e} with the listener.

While I see {be'enai} as correct grammar, I can't figure out a meaning for it beyond "Ha ha, I know a cmavo you don't!"

''To me, {be'enai} seems fairly obvious: "Permission not to speak?" which could be used in a fairly similar way to "No comment!" but asking permission not to comment rather than refusing.''

je'e
{je'e} acknowledges that the speaker heard and understands the last utterance. As with most vocatives, I can follow {je'e} and {je'enai} with the name of the listener.

In English, people acknowledge "Thank you.", with "Welcome.". They say "I heard." to acknowledge they heard the last utterance. They say "I understand." To point out they understand the last utterance. "Okay." also acknowledges the last utterance, but carries more hint of agreement than {je'e}. To show that nearly anyone would understand an utterance, English speakers sometimes use the word "Duh!".

{je'enai} means the opposite of {je'e}. It means "I did not hear and/or I did not understand."

In English people say "Huh?" or "Wha?" or "What?" to denote similar meanings.

co'o
A Lojban speaker says {co'o} to another Lojban speaker shortly before ending conversation or close proximity to the second Lojban speaker. The second Lojban speaker often replies {co'o}. As with most other vocatives, I can follow {co'o} with a name.

English phrases with similar meanings include "Goodbye.", "So long.", and "See you later.".

{co'onai} means the opposite of {co'o}, but Lojban speakers seem to prefer {coi} to express this meaning nearly unanimously. I like {coi} better because it has two less syllables.

re'i
This word signifies that the speaker can listen to the listener. I can follow {re'i} with a name like most vocatives to signify the listener.

English phrases with similar meanings include "Go ahead.", "I'm all ears.", and "I'm listening."

la daniel. cusku zo be'e .i la kleir. cusku zo re'i Daniel says, "May I have a word with you?". Claire says, "Go ahead.".

{re'inai} means the opposite of {re'i}. Therefore it means the speaker cannot listen to the listener.

In English {re'inai} translate to "Sorry, I'm busy.", "I'm not accepting visitors.", and "I can't listen right now."

zo
{zo} quotes the next word. By quoting the next word, a speaker can refer to a word as a word instead of as its meaning. {zo broda} has about the same meaning as {lu broda li'u}, but {zo} can only quote one word.

In English, I might put a word in quotes italics to quote it. If I only wanted to quote one word, I might say "the word foo".

I can talk about the word {zo} as a word by saying {zo zo}. {zo nai} quotes the word {nai} instead of meaning the opposite of {zo}.

ma
In asking another Lojban speaker for information, a Lojban speaker might say give a bridi describing their information with a blank for the listener to insert their answer. The asker would signify that blank with {ma}. The answerer would probably not repeat the entire le bridi, but instead just the information to replace {ma} with.

In English, a person might say "What" or "blank" instead.

la
{la} must go before names, except names in vocatives where the speaker can replace it with a mandatory pause. English has no article for names. For non-names it has the articles "a", "an", and "the".

zo la gadri {la} is an article.

mi
{mi} refers to the speaker or author. An English speaker would probably say "me" to mean the same. I pronounce both the same.

If I wanted to say something that didn't mean much. I would say, {mi'e mi}, pointing out the speaker as myself.

Does {minai} mean {do}?

I believe that {minai} would mean anyone but yourself.

gismu
smuni mun smu     meaning x1 is a meaning/interpretation of x2                   recognized/seen/accepted by x3                    [referential meaning (=selsni, snismu)]; (cf. jimpe,                    sinxa, valsi, tanru, gismu, lujvo, cmavo, jufra)

gismu gim    gi'u root word x1 is a (Lojban) root word expressing relation x2                   among argument roles x3, with affix(es) x4                    [gismu list, if physical object (= (loi) gimste); referring to the mental construct (e.g. propose adding                   a new gismu to the gismu list = gimpoi, gimselcmi,                    gimselste)]; (cf. cmavo, cmene, lujvo, smuni, sumti,                    tanru, valsi)

lujvo luv jvo     affix compound x1 (text) is a compound predicate word with meaning x2 and arguments x3 built from metaphor x4                   (cf. stura, cmavo, gismu, rafsi, smuni)

tanru        tau  phrase compound x1 is a binary metaphor formed with x2 modifying x3, giving meaning x4 in usage/instance x5                   (x2 and x3 are both text or both si'o concept) (cf. gismu, smuni)

sumti sum    su'i argument x1 is a/the argument of predicate/function x2 filling place x3 (kind/number) (x1 and x2 are text); (cf. bridi, darlu, gismu)

bridi    bri      predicate x1 (text) is a predicate relationship with relation x2 among arguments (sequence/set) x3                   [also: x3 are related by relation x2 (= terbri                    for reordered places)]; (x3 is a set completely                    specified); (cf. sumti, fancu)

cmavo        ma'o structure word x1 is a structure word of grammatical class x2, with meaning/function x3 in usage (language) x4                   [x4 may be a specific usage (with an embedded language                    place) or a massified language description; x3 and x4                    may be merely an example of cmavo usage or refer to                    an actual expression; cmavo list, if physical object (= (loi) ma'oste); referring to the mental construct (e.g. propose adding a new cmavo to the cmavo list =                   ma'orpoi, ma'orselcmi, ma'orselste)]; (cf. gismu,                    lujvo, gerna, smuni, valsi)

cmene    cme me'e name x1 (quoted word(s)) is a/the name/title/tag of x2                   to/used-by namer/name-user x3 (person) [also: x2 is called x1 by x3 (= selcme for reordered                   places)]; (cf. cmavo list me'e, gismu, tcita,                    valsi, judri)

Exercises
In Exercises 1 to 11, translate the Lojban sentence to English. 1. coi. braun. e'apei mi ba te cmene do lu la bab. li'u 2. be'e meiris. mi'o ca cliva 3. ko'a cusku lu le lujvo cu lujvo li'u .i ko'e cusku zo je'e 4. ko'a cusku lu mi cmavo li'u .i ko'e cusku lu je'enai li'u 5. co'o .ednas. ko ba klama mi 6. la daniel. cusku zo be'e .i la kleir. cusku zo re'i 7. mi cusku lu be'e. reitcel. li'u le nanmu pe la reitcel. cusku lu la reitcel. cusku lu re'inai li'u li'u 8. mi cusku zo bridi .i mi na cusku tanru 9. mi cusku lu lu smuni cmene li'u tanru ma ma li'u .i la keven. cusku lu smuni cmene li'u tanru zo smuni zo cmene li'u 10. mi'e la mark. 11. le prenu pe mi te cmene mi lu la brai'an. li'u

In Exercises, 100 to 131, translate le jufra (the sentence) given. 100. le se bridi cu smuni le selbri mi .i 101. zo coi smuni zoi gy. hello .gy mi .i 102. gy. goodbye .gy smuni zo co'o mi .i 103. lu mi'e. brai'an. li'u smuni lu mi me la brai'an. li'u mi .i 104. fi la'o smuni. George Bush .smuni goi ko'a smuni fa ko'a la'o smuni. Mr. President .smuni .i 105. le ve gismu cu smuni le rafsi mi .i 106. zoi ly. gi'u .ly ve gismu zo gismu .i 107. zo smuni gismu .i 108. zo gismu gismu fi le te gismu .i 109. zo selbri gismu le du'u se bridi .i 110. zo selbri lujvo lu se bridi li'u .i 111. zo selbri lujvo zo'e le te lujvo be fa zo bridi .i 112. zo selbri se ve se lujvo lu se bridi li'u .i 113. zo selma'o lujvo fo lu se cmavo li'u .i 114. zo selma'o lujvo fi le se cmavo .i 115. zo selma'o lujvo lu se cmavo li'u le ve cmavo lu se cmavo li'u .i 116. zo selbri lujvo lu se bridi li'u le bridi lu se bridi li'u .i 117. zo tertau lujvo lu te tanru li'u le tanru lu te tanru li'u .i 118. lu gismu smuni li'u tanru zo gismu zo smuni .i 119. lu gismu lujvo li'u tanru zo gismu zo lujvo lu gismu co lujvo li'u .i 120. lu le tanru li'u cu smuni lu le ve lujvo li'u mi .i 121. zo tanru gismu zo'e le se tanru zoi ly. tau .ly .i 122. le gismu sumti dei li pa .i 123. nei sumti dei li re .i 124. li ci sumti dei li ci .i 125. zo sumti gismu .i zo sumti sumti di'u li pa .i 126. mi klama le se klama le te klama .i le te klama sumti di'u li ci .i 127. dei bridi le du'u bridi dei 128. lu le ninmu klama le nanmu li'u bridi le du'u klama le nanmu 129. do nanmu .i di'u bridi le du'u nanmu do .i 130. di'e bridi le du'u cliva la'o gy. Elvis .gy .i la'o gy. Elvis .gy cliva .i 131. zo .ui cmavo zoi selma'o. UI .selma'o lu mi gleki li'u la lojban.

In Exercises 200 to 226, give an English translation of each place of each le sumti given. 201. le smuni 202. le se smuni 203. le te smuni 204. le gismu 205. le se gismu 206. le te gismu 207. le ve gismu 208. le lujvo 209. le se lujvo 210. le te lujvo 211. le ve lujvo 212. le tanru 213. le se tanru 214. le te tanru 215. le ve tanru 216. le xe tanru 217. le sumti 218. le se sumti 219. le te sumti 220. le bridi 221. le se bridi 222. le te bridi 223. le cmavo 224. le se cmavo 225. le te cmavo 226. le ve cmavo

'''In Exercises 301 to 321, use the best word in the vocabulary of this lesson to fill in each blank of each sentence. You may use each word more than once.''' 301. Teacher: _____ is the capital of Kentucky? Pupil: Frankfort. 302. Mother: Did you hear what I just said? Daughter: _____, except I missed the part about chocolate. 303. I said "_____", and she told me, "Sorry, I can listen right now." 304. _____ name is Jessica, but my friends call me Jessie. 305. Welcome to _____ .alaskas.! 306. When I say "_____ Eliza", that means I'm talking to you. 307. I wish I could stay longer. _____ 308. If I knew le _____, I wouldn't have asked you for a definition. 309. Say "doi" and then le _____ of the person you wish to talk to. 310. _____ Robert! It's so nice to see you after all these years. 311. I wouldn't have said "_____" if I wasn't all ears. 312. Did you rent the movie, "_____, Myself & Irene"? 313. Which le rafsi did you use to make that le _____? 314. How can you call that le _____, when a phrase compound needs at least two words? 315. If f(x) = y, then f is the function and yby. _____ fy. 316. That's na ____ because any decent predicate needs at least pa le selbri. 317. ro le attitudinals are a type of word called le _____. 318. _____, but I would feel happy to listen another time. 319. ____ la romeos. _____ la romeos. Wherefore art thou Romeo? 320. _____ blue begins with the letter "b". 321. Lojban has 1342 le _____.

Answers to exercises
1. Hello Brown. May I call you Bob? 2. May I have a word with you, Mary? Let's leave. The Lojban means more "We leave." than the English. Maybe I could change that with an attitudinal meaning "suggestion" or {ko} and {mi} instead of {mi'o}. 3. The first person says, "The affix compound qualifies as an affix compound." The second person says, "I understand." 4. The first person says, "I qualify as a structure word.". The second person says, "Huh?". 5. Goodbye, Edna. Come see me in the future. 6. Daniel says, "May I have a word with you?". Claire says, "Go ahead.". 7. I said, "May I speak with you, Rachel?" The man associated with Rachel said, "Rachel said, 'I can't listen right now.'" 8. I said the word {bridi}. I did not say the word {tanru}. 9. I said, "What modifies what in the metaphor 'meaning sort of name'?" Kevin said, "In the metaphor 'meaning sort of name', 'meaning' modifies 'name'." 10. I go by the name Mark. 11. People associated with me call me "Brian".

100. According to me, "the relationship of a sentence" means "the relationship of a sentence". 101. I see "Hello" meaning {coi}. 102. I see {co'o} as meaning "Goodbye". 103. I accept the interpretation "I am Brian." for the sentence "I am Brian.". 104. George Bush accepts the interpretation of Mr. President as himself. 105. I recognize the interpretation of the affixes of a root word as the affixes of a word. 106. The word {gismu} (meaning root word) has the affix {gi'u}. 107. The word {smuni} qualifies as a root word. 108. The relationship of the word {gismu} has a role for the roles of the relationship of a root word. 109. The word {selbri} denotes the relationship {se bridi}. 110. The affix compound {selbri} means {se bridi}. 111. The relationship of the compound word {selbri} has the same roles as the compound word {bridi}. 112. The compound word {selbri} comes from the metaphor {se bridi}. 113. The word {selma'o} comes from the metaphor {se cmavo}. 114. The relationship of the word {selma'o} involves the grammatical class of a structure word. 115. The compound word {selma'o} means {se cmavo}, and its relationship involves its meaning, and it comes from the metaphor {se cmavo}. 116. The compound word {selbri} means {se bridi}, and its relationship involves the predicate, and it comes from the metaphor {se bridi}. 117. The compound word {tertau} means {te tanru}, and its relationship involves a binary metaphor, and it comes from the metaphor {te tanru}. 118. "Root word sort of meaning" qualifies a binary metaphor with "root word" modifying "meaning". 119. In binary metaphor "Root word sort of compound word", "root word" modifies "compound word", and it means "compound word of root word sort". 120. According to me, "metaphor made into compound word" means "binary metaphor". 121. The root word {tanru} denotes the relationship involving the modifier of the metaphor, and has the affix {tau}. 122. The root word is in the current utterance filling the first role. 123. The current utterance is in the current predicate filling the second role. 124. Three is in the current utterance filling the third role. 125. The word {sumti} qualifies as a root word. The word {sumti} is in the previous utterance filling the first role. 126. I go to the destination from the origin. The destination is in the previous utterance filling the third place. 127. The current utterance qualifies as a predicate with the predicate relationship and the role the current utterance. 128. The predicate "The woman goes to the man." involves the going relationship and the role of the man. 129. You qualify as a man. The last utterance involves the man relationship and the argument you. 130. The next utterance qualifies as a predicate involving the leaving relationship and Elvis. Elvis leaves. 131. The structure word {.ui} comes from the grammatical class {UI}, means I feel happiness, and is used in the Lojban language.

201. meaning 202. symbol with meaning 203. interpreter of meaning 204. root word 205. relationship expressed by root word 206. roles in relationship expressed by root word 207. affixes of root word 208. compound word 209. meaning of compound word 210. roles of relationship of compound word 211. metaphor used to make compound word 212. binary metaphor 213. modifier of metaphor 214. modified of metaphor 215. meaning of metaphor 216. usage of metaphor 217. argument 218. predicate of argument 219. role filled by argument 220. predicate 221. relationship of predicate 222. argument of predicate 223. structure word 224. grammatical class of structure word 225. meaning of structure word 226. language of structure word

301. ma 302. je'e 303. be'e 304. mi 305. la 306. doi 307. co'o 308. smuni 309. cmene 310. coi 311. re'i 312. mi 313. lujvo 314. tanru 315. sumti 316. bridi 317. cmavo 318. re'inai 319. doi, doi 320. zo 321. gismu

title: Lojban/Vocabulary 1


text:
Physics Study Guide/Sound

Sound is defined as mechanical sinosodial vibratory longitudinal impulse waves which oscillate the pressure of a transmitting medium by means of adiabatic compression and decompression consequently resulting in the increase in the angular momentum and hence rotational kinetic energy of the particles present within the transmitting medium producing frequencies audible within hearing range, that is between the threshold of audibility and the threshold of pain on a Fletchford Munson equal loudness contour diagram.

Intro
When two glasses collide, we hear a sound. When we pluck a guitar string, we hear a sound.

Different sounds are generated from different sources. Generally speaking, the collision of two objects results in a sound.

Sound does not exist in a vacuum; it travels through the materials of a medium. Sound is a longitudinal wave in which the mechanical vibration constituting the wave occurs along the direction of the wave's propagation.

The velocity of sound waves depends on the temperature and the pressure of the medium. For example, sound travels at different speeds in air and water. We can therefore define sound as a mechanical disturbance produced by the collision of two or more physical quantities from a state of equilibrium that propagates through an elastic material medium.

=Sound=

The amplitude is the magnitude of sound pressure change within a sound wave. Sound amplitude can be measured in pascals (Pa), though its more common to refer to the sound (pressure) level as Sound intensity(dB,dBSPL,dB(SPL)), and the perceived sound level as Loudness(dBA, dB(A)). Sound intensity is flow of sound energy per unit time through a fixed area. It has units of watts per square meter. The reference Intensity is defined as the minimum Intensity that is audible to the human ear, it is equal to 10-12 W/m2, or one picowatt per square meter. When the intensity is quoted in decibels this reference value is used. Loudness is sound intensity altered according to the frequency response of the human ear and is measured in a unit called the A-weighted decibel (dB(A), also used to be called phon).

The Decibel
The decibel is not, as is commonly believed, the unit of sound. Sound is measured in terms of pressure. However, the decibel is used to express the pressure as very large variations of pressure are commonly encountered. The decibel is a dimensionless quantity and is used to express the ratio of one power quantity to another. The definition of the decibel is $$10\cdot \log_{10}\left(\frac{x}{x_0}\right)$$, where x is a squared quantity, ie pressure squared, volts squared etc. The decibel is useful to define relative changes. For instance, the required sound decrease for new cars might be 3 dB, this means, compared to the old car the new car must be 3 dB quieter. The absolute level of the car, in this case, does not matter.

Definition of terms
Sample equation: Change in sound intensity Δβ	= β2 - β1 = 10 log(I2/I0) - 10 log(I1/I0) = 10 [log(I2/I0) - log(I1/I0)] = 10 log[(I2/I0)/(I1/I0)] = 10 log(I2/I1) where log is the base-10 logarithm.

Doppler effect
f' is the observed frequency, f is the actual frequency, v is the speed of sound ($$ v=336+0.6T $$), T is temperature in degrees Celsius $$v_0$$ is the speed of the observer, and $$v_s$$ is the speed of the source. If the observer is approaching the source, use the top operator (the +) in the numerator, and if the source is approaching the observer, use the top operator (the -) in the denominator. If the observer is moving away from the source, use the bottom operator (the -) in the numerator, and if the source is moving away from the observer, use the bottom operator (the +) in the denominator.

Example problems
A. An ambulance, which is emitting a 400 Hz siren, is moving at a speed of 30 m/s towards a stationary observer. The speed of sound in this case is 339 m/s.

$$f' = 400\,\mathrm{Hz} \left( \frac{339 + 0}{339 - 30} \right)$$

B. An M551 Sheridan, moving at 10 m/s is following a Renault FT-17 which is moving in the same direction at 5 m/s and emitting a 30 Hz tone. The speed of sound in this case is 342 m/s.

$$f' = 30\,\mathrm{Hz} \left( \frac{342 + 10}{342 + 5} \right)$$

title: Physics Study Guide/Sound


text:
Physics Study Guide/Reviews

Our first review of the Physics Study Guide is in, by email to the author:

'''Thanks karl!  it's very helpful!!!! '''

title: Physics Study Guide/Reviews


text:
Physics Study Guide/Torque

Torque and Circular Motion
Circular motion is the motion of a particle at a set distance (called radius) from a point. For circular motion, there needs to be a force that makes the particle turn. This force is called the 'centripetal force.' Please note that the centripetal force is not a new type of force-it is just a force causing rotational motion. To make this clearer, let us study the following examples: Thus, we see that the centripetal force acting on a body is always provided by some other type of force -- centripetal force, thus, is simply a name to indicate the force that provides this circular motion. This centripetal force is always acting inward toward the center. You will know this if you swing an object in a circular motion. If you notice carefully, you will see that you have to continuously pull inward. We know that an opposite force should exist for this centripetal force(by Newton's 3rd Law of Motion). This is the centrifugal force, which exists only if we study the body from a non-inertial frame of reference(an accelerating frame of reference, such as in circular motion). This is a so-called 'pseudo-force', which is used to make the Newton's law applicable to the person who is inside a non-inertial frame. e.g. If a driver suddenly turns the car to the left, you go towards the right side of the car because of centrifugal force. The centrifugal force is equal and opposite to the centripetal force. It is caused due to inertia of a body.
 * 1) If Stone ties a piece of thread to a small pebble and rotates it in a horizontal circle above his head, the circular motion of the pebble is caused by the tension force in the thread.
 * 2) In the case of the motion of the planets around the sun (which is roughly circular), the force is provided by the gravitational force exerted by the sun on the planets.

 * $$\omega_{\text{avg}}=\frac{\omega+\omega_f}{2}=\frac{\theta}{t}$$

Average angular velocity is equal to one-half of the sum of initial and final angular velocities assuming constant acceleration, and is also equal to the angle gone through divided by the time taken.

 * $$\alpha=\frac{\Delta\omega}{t}$$

Angular acceleration is equal to change in angular velocity divided by time taken.

Angular momentum
Angular momentum of an object revolving around an external axis $$O$$ is equal to the cross-product of the position vector with respect to $$O$$ and its linear momentum.

Angular momentum of a rotating object is equal to the moment of inertia times angular velocity.

 * $$L=I\omega$$

 * $$\tau=I\alpha=\frac{\Delta L}{t}$$>

Rotational Kinetic Energy is equal to one-half of the product of moment of inertia and the angular velocity squared.

The equations for rotational motion are analogous to those for linear motion-just look at those listed above. When studying rotational dynamics, remember:
 * IT IS USEFUL TO NOTE THAT

 * the place of force is taken by torque

 * the place of mass is taken by moment of inertia

 * the place of displacement is taken by angle

 * the place of linear velocity, momentum, acceleration, etc. is taken by their angular counterparts.

title: Physics Study Guide/Torque


text:
Lojban/Vocabulary

Vocabulary 1
See Vocabulary 1.

 * doi
 * coi
 * be'e
 * je'e
 * je'enai
 * co'o
 * re'i
 * re'inai
 * zo
 * ma
 * la
 * mi

 * smuni
 * gismu
 * lujvo
 * tanru
 * sumti
 * bridi
 * cmavo
 * cmene

Vocabulary 2
See Vocabulary 2.

 * le
 * cu
 * ti
 * ta
 * tu
 * goi
 * ko'a
 * zo'o
 * zo'onai

 * broda
 * blanu
 * cusku
 * ciska
 * prenu
 * remna
 * nanmu
 * ninmu
 * gasnu
 * zukte
 * rinka

title: Lojban/Vocabulary


text:
Lojban/Vocabulary 2

Word list

 * le
 * cu
 * ti
 * ta
 * tu
 * goi
 * ko'a
 * zo'o
 * zo'onai

 * broda
 * blanu
 * cusku
 * ciska
 * prenu
 * remna
 * nanmu
 * ninmu
 * gasnu
 * zukte
 * rinka

cmavo
le       LE       the described non-veridical descriptor: the one(s) described as ...

cu       CU       selbri separator elidable marker: separates selbri from preceding sumti, allows preceding terminator elision

ti       KOhA6    this here pro-sumti: this here; immediate demonstrative it; indicated thing/place near speaker

ta       KOhA6    that there pro-sumti: that there; nearby demonstrative it; indicated thing/place near listener

tu       KOhA6    that yonder pro-sumti: that yonder; distant demonstrative it; indicated thing far from speaker&listener

goi      GOI      pro-sumti assign sumti assignment; used to define/assign ko'a/fo'a                   series pro-sumti; Latin 'sive'

ko'a     KOhA4    it-1 pro-sumti: he/she/it/they #1 (specified by goi)

zo'o     UI5      humorously attitudinal modifier: humorously - dully - seriously

cf. xajmi, junri)

zo'onai  UI*5     seriously attitudinal modifier: humorously - dully - seriously

gismu
broda rod         predicate var 1 1st assignable variable predicate (context determines                   place structure)

(cf. cmavo list bu'a)

blanu    bla      blue x1 is blue [color adjective]

(cf. skari, blabi, xekri, zirpu, kandi, carmi, cicna)

cusku cus sku     express x1 (agent) expresses/says x2 (sedu'u/text/lu'e                   concept) for audience x3 via expressive medium x4

[also says]; (cf. bacru, tavla, casnu, spuda, cmavo                   list cu'u, bangu, dapma, jufra, pinka)

ciska        ci'a write                ' scribe ' x1 inscribes/writes x2 on display/storage medium x3 with writing implement x4; x1 is a scribe

[also x3 writing surface]; (cf. papri, penbi,                     pinsi, tcidu, xatra, pixra, prina, finti for                      'author' or specific authorial works, barna, pinka)

prenu    pre      person x1 is a person/people (noun) [not necessarily human]; x1 displays personality/a persona

(cf. nanmu, ninmu, remna, zukte, sevzi)

remna rem    re'a human x1 is a human/human being/man (non-specific                   gender-free sense); (adjective:) x1 is human

(cf. nanmu, ninmu, prenu)

nanmu        nau  man x1 is a man/men; x1 is a male humanoid person [not necessarily adult]

[word dispreferred in metaphor/example as sexist; (use remna or prenu)]; (cf. ninmu, remna, prenu,                   makcu, nanla, bersa)

ninmu nim    ni'u woman                ' women ' x1 is a woman/women; x1 is a female humanoid person [not necessarily adult]

[word dispreferred in metaphor/example as sexist; (use remna or prenu)]; (cf. nanmu, remna, prenu,                     makcu, nixli)

gasnu        gau  do                    x1 [person/agent] is an agentive cause of event x2; x1 does/brings about x2

(cf. cmavo list gau, gunka, zukte, rinka, fasnu for                   non-agentive events, jibri, kakne, pilno)

zukte zuk    zu'e act x1 is a volitional entity employing means/taking action x2 for purpose/goal x3/to end x3

[also acting at, undertaking, doing; agentive cause with volition/purpose; also x3 objective, end]; (cf. cmavo list zu'e, bapli, gunka, jalge, krinu,                   mukti, rinka, snuti, gasnu, fasnu, minji, prenu,                    ciksi, jibri, pilno, pluta, tadji, tutci)

rinka rik    ri'a cause x1 (event/state) effects/physically causes effect x2                   (event/state) under conditions x3

[x1 is a material condition for x2; x1 gives rise to                   x2]; (cf. gasnu, krinu, nibli, te zukte, se jalge,                    bapli, jitro, cmavo list ri'a, mukti, ciksi, xruti)

title: Lojban/Vocabulary 2


text:
French/Appendices/Typing characters

French accents on computers
While French keyboards are available, some French students may need to enter accented characters on an English keyboard.

If you are on the Internet, many sites have a virtual keyboard that allows you to mouse-select the characters. Google Translate, for example, has a virtual keyboard icon for entering text in the form window.

Windows Operating System
If you are using Microsoft Windows Operating System, then you can use the Character Map application, located under:
 * Start->Programs->Accessories->System Tools->Character Map (Send this application to your desktop for better ease of use)

Some word processing programs allow the user to enter accents using a key combination, while others may require an Alt code.

The ALT code is entered by holding down the ALT key, and enter the number (all digits given) using the keypad (only the keypad).

In most applications, you will need the numlock turned on to avoid undesirable effects.

Mac Operating System
If you are using the Mac Operating System, there is a simple system that can be used with the Option (⌥) key. Open the System Preferences application (found in your Applications folder by default and in the Apple menu in the upper-left corner) and navigate to "Language and Text" preferences. Under the Input Sources tab, select U. S. Extended. Now you can use the following key combinations with the Option (⌥) key to form French accents.

For instance: Press and hold ⌥ and then press e. Now you have a floating acute accent. Press e again to put the accent over that letter and form é. In the same way ⌥ - 6, then o will give you ô, etc. These shortcuts work throughout the operating system and do not depend on the application in which they are used.

Linux Operating System
If you are using Ubuntu Linux with Gnome you select the Compose key from System: Preferences: Keyboard then Layouts: Layout Options: Compose key position. You can select one of Right Alt key, Left Win-key, Right Win-key, Menu key, Right Ctrl key or Caps Lock key (for a USA keyboard layout). The Keyboard preferences dialog has an area you can use to test the settings. See below for how to use the Compose key. Ubuntu with a different window manager, such as KDE should have a similar keyboard preferences utility.

If you are using Unix or a derivative operating system (such as Linux) with XFree86, you can define a compose key by opening a terminal window and typing:

'To use the Windows menu key (between the right Windows key and right Ctrl key:
 * xmodmap -e "keysym Menu = Multi_key"

'To use the right Windows key:
 * xmodmap -e "keysym R_Meta = Multi_key"

'To use the right Alt key:'
 * xmodmap -e "keysym Alt_Gr = Multi_key"

To use the Compose key, press and release the Compose key, then type two characters. Combinations useful for typing in French follow:

 * à Compose + a + `
 * â Compose + a + ^
 * ä Compose + a + "

 * ç Compose + c + ,

 * è Compose + e + `
 * é Compose + e + '
 * ê Compose + e + ^
 * ë Compose + e + "
 * É Compose + E + '

 * î Compose + i + ^
 * ï Compose + i + "

 * ô Compose + o + ^
 * ö Compose + o + "

 * ù Compose + u + `
 * û Compose + u + ^
 * ü Compose + u + "

title: French/Appendices/Typing characters


text:
Physics Study Guide/Waves

=Waves= Wave is defined as the movement of any periodic motion like a spring, a pendulum, a water wave, an electric wave, a sound wave, a light wave, etc.

Any periodic wave that has amplitude varied with time, phase sinusoidally can be expressed mathematically as
 * R(t, θ) = R Sin (ωt + θ)

 * Minimum wave height (trough) at angle 0, π, 2π, ...
 * F(R,t,θ) = 0 at θ = nπ

 * Maximum wave height (peak or crest) at π/2, 3π/2, ...
 * F(R,t,θ) = R at θ = (2n+1)π/2

 * Wavelength (distance between two crests) λ = 2π.
 * λ = 2π - A circle or a wave
 * 2λ = 2(2π) - Two circles or two waves
 * kλ = k2π - Circle k or k amount of waves

 * Wave Number,
 * k

 * Velocity (or Angular Velocity),
 * ω = 2πf

 * Time Frequency,
 * f = 1 / t

 * Time
 * t = 1 / f

Wave speed is equal to the frequency times the wavelength. It can be understood as how frequently a certain distance (the wavelength in this case) is traversed.

Frequency is equal to speed divided by wavelength.

Period is equal to the inverse of frequency.

Variables

Definition of terms

Image here

The wave’s extremes, its peaks and valleys, are called antinodes. At the middle of the wave are points that do not move, called nodes.

Examples of waves: Water waves, sound waves, light waves, seismic waves, shock waves, electromagnetic waves …

Oscillation
A wave is said to oscillate, which means to move back and forth in a regular, repeating way. This fluctuation can be between extremes of position, force, or quantity. Different types of waves have different types of oscillations.

Longitudinal waves: Oscillation is parallel to the direction of the wave. Examples: sound waves, waves in a spring.

Transverse waves: Oscillation is perpendicular to direction of the wave. Example: light

Interference
When waves overlap each other it is called interference. This is divided into constructive and destructive interference.

Constructive interference: the waves line up perfectly and add to each others’ strength.

Destructive interference: the two waves cancel each other out, resulting in no wave.This happens when angle between them is 180degrees.

Resonance
In real life, waves usually give a mishmash of constructive and destructive interference and quickly die out. However, at certain wavelengths standing waves form, resulting in resonance. These are waves that bounce back into themselves in a strengthening way, reaching maximum amplitude.

Resonance is a special case of forced vibration when the frequency of the impressed periodic force is equal to the natural frequency of the body so that it vibrates with increased amplitude, spontaneously.

title: Physics Study Guide/Waves


text: User:Dgrant~enwikibooks

title: User:Dgrant~enwikibooks


text:
Talk:German/Grammar/Alphabet and Pronunciation

How to Play Audios
The Sample audio, what program to i need to listin to it? Andrewcool
 * Good question. I'll need to research that.  It just plays "automatically" when I click on it, so I think any PC media player ? - marsh

When i open it, it doesn't open automatic. It wants me to choose the program to open it but so far i have not found one that works.
 * Yes, Windows does give me that "choice" too. My computer has AudioCentral by Roxio and that plays the file just fine, but I seem to recall that the default Windows media player also worked ok. - marsh 17:47, 27 Mar 2005 (UTC)

Well we can covert the .ogg and make them into .wav for people who are having problems with this. -Andrewcool
 * Sounds good to me. I've got to admit, I know nothing about sound files - marsh 03:53, 29 Mar 2005 (UTC)

Well wiki only wants .ogg so that means we will need somebody else to host it.--Andrewcool 23:54, 30 Mar 2005 (UTC)

Foobar works well. google it. -thisdude415

 * Get the OGG codec. Google that.

The Description Of Sounds
The long and short 'a' sounds are not very different. For example, I would say the 'a' in father and the 'o' in pot are about the same, only the first (father) is strung out a bit more (ahhhh vs ah). When I try this in German I see about the same difference: haben = ahhhh, acht = ah. In English, these would both be short vowel sounds. Am I missing something, or is that all there is to it? Is there a better way to differentiate the long and short 'a' in German? Is it really correct to call these long and short vowel sounds? -- Marsh 18:30, 5 Nov 2003 (UTC)

 * Hey Marsh! I'd say, you got it completely right. But there is a third sound in German sometimes discriped as an "a"-sound. It's the sound of "-er" at the ending of a word (e.g. Keller = Basement). This sound is somewhere between kell-ea and Kell-a. Think of how it's pronounced in rap slang (kill-a) or of the way Bob Marley pronounced Rast-a. -- Guido

 * Hi, I've to say, taht is not right. It's maybe a bit slang, but someone speaking real good german would say kell-er and not kella. I do it myself, but I know that's because of my accent. -louisana

The Ö-Laut
Hey to all out there. What do you think: does the short Ö (as in 'Köln') sound like the 'ear' in a (British pronounced) "heard". To me it does.

 * British "ear" in "heard" is IMHO more similar to a long Ö (as in 'hören'); but in general, "heard" should be mentioned as a guideline for pronouncing 'ö'. The existing explanation is good however (I was not aware that the 'Ö' from my native country's name had anything to do with whistling or the sound in 'late', but following those instructions works!).

Examples not useful
is to my mind a bit poor. I know, English textbooks for German explain sounds that way. And they will not break a habit. Result: an unacceptable pronunciation. Let us see how the German "e" is explained: as in lay with no movement. What movement? Movement of the tongue. Okay. But is there any English speaking person aware of that movement? The result would be better if a sound like in "get" is made long. And that would exactly be what it is: a German e.

 * I think that means no movement in the sound (not physical movement), although obviously to move or alter a sound there must be some subtle movement of the speech apparatus. Making the "e" in "get" long would sound like "e" in "week". A "long" e in English is not a long "e" in German or even close. Coming from the English speaking perspective, the explanations are pefectly sensible. - marsh

I fully agree that the German e is, in fact, the same sound as the e in "get" made long; just keep your mouth and tongue in the same position and keep the air going. The "e" in "week" has nothing to do with the "e" in "get", that's just an artifact of English orthography. The description based on "lay" might be good because it explicitly warns about the most common pronounciation mistake that English speaking people make; on the other hand, it is far less useful to people who already speak other languages besides English.

 * I disagree, that the German long "e" is the "e" in "get" made long, and I am myself a German native speaker. Actually, the "e" sound in "get" ([ɛ] in IPA) pronounced as long vowel [ɛː] is closer to the German long "ä" than to the long "e" ([eː]). Unfortunately, also many German native speakers don't use or know the [ɛː] sound and pronounce the long "ä" just like the long German "e", especially in the north of Germany. --Tobulax 07:51, 25 July 2007 (UTC)

Austrian Pronunciation
There are two important differences in how German is pronounced in Austria from what is described here. I'm not talking about dialects, just the most important basic differences, analogous to the differences in British and American English. For one, the "s" in Austrian is not pronounced as a 'z' at the start of a word, e.g. in "Sonne". AFAICT, it may only be pronounced 'z' when it is between two vowels, e.g. "Rose". Also, "ig" as in richtig is NOT pronounced as an ich-sound, but rather as "i"+"g". Would it be more appropriate to mention these differences in the text where the letters are described (as is already done to describe the absence of "ß" in Switzerland), or should a separate short section outlining the differences be added at the end, in order to keep things simpler for people who just want to learn the "dominant" form of German?
 * I agree it is a good idea to bring up these differences and I would think that mentioning it where specifically appropriate (as with the Swiss example) would be best - marsh 04:37, 31 May 2005 (UTC)

Done. WolfgangThaller 03:56, 3 Jun 2005 (UTC)

Pronunciation of German alphabet
The one thing that is always ailing me is that almost all german textbooks present the sound of german alphabets by means of using similiar english words, like "bay", "ah". Many of those descriptions are pretty vague actually like "Slightly more dental" for L and some are absent like Ü. I suggest presenting those alphabets with IPA which is more convenient for linguistically more advanced users.

 * Not to mention that this pronunciation system is just plain wrong in many cases. I'd be willing to help IPA it. - 71.136.181.45 08:59, 13 January 2007 (UTC)

The German Alphabet - oggfile
I think the ogg-file is not that good. I would speak it again, if you need it. Just contact me on meta. I also could speak more, if you want to. m:User:Louisana
 * If you can create a better one, by all means please do. I have not the technical skills to create sound files - marsh 05:05, 10 August 2005 (UTC)

Done. For further request please use my meta talk page! Also spoke something here m:User:Louisana

Syllable stress: It's not that easy!
It's not generally correct that always the first syllable is stressed. For words with prefix or suffix syllables, it becomes more complex. A a native German, I never learnt formal rules for that, but in most cases the first syllable of the stem of the word (without pre- and suffixes) is stressed, but there are lots of exceptions. Those who know German, confer Wortakzent, with the example of umfahren (to knock over) vs. umfahren (to drive round). --Langec 20:56, 18 June 2006 (UTC)

First alphabet audio file appears to be bogus
After the table showing the alphabet there are two audio files which are fine.

But in the title for the table, where you see "German Dialogue • Alphabet • audio", the audio link is to a file "German Dialogue - The alphabet.ogg".

This file was uploaded in November 2006 by Paulaburesh who is no longer a registered user.

The history page for this file is.

This file is not an OGG file (I've looked at the binary data and it does not start with the sequence "OggS" as it should).

I suggest it be deleted.

Pronunciation of the alphabet in the German language
I have noticed some weird ideas on the pronunciation of the alphabet in the German language. The letter b is never pronounced as a 'p' unless one hails from "Payern" (= Bayern/Bavaria). The letter g is not really pronounced as a 'k' at the end of a word, but like in English as a hard 'g', or softened to a German 'ch' like in Bach or ich. One should always be aware -especially as a non-German- that the German pronunciation has a tremendous variation dependent on the region; Austrian or Swiss German is certainly not the standard. PS I myself am a 'Grenzer' from the Netherlands with a severe German accent, which I was born with.

More sound examples please
A lot of discussion could be made moot if the page would include sound examples of individual words to illustrate how it is really pronounced. This prevent a lot of confusion. E.g. the page says that short i is pronounced as the i in English pit. To my ears -Dutch ones- that is not really true. German mit and English Mitt are not the same. Sound files please.

Jcwf (discuss • contribs) 17:56, 19 May 2015 (UTC)


text:
User:Colipon

Wikibooks is great.

title: User:Colipon


text:
User talk:Colipon

Welcome Colipon! This place is a little more laid back than Wikipedia as there are usually only a small handfull working here at any one time (like VfD hardly exists - actually it may not exist?). But lots to be done here as at Wikipedia, and I suspect this place is headed for bigger things involving more contributors. All helping hands welcome - Marsh 03:13, 6 Nov 2003 (UTC)

title: User talk:Colipon


text:
Talk:Discrete Mathematics

Why is "polynomials and number theory" presented before "rings, fields and modules", which is in turn presented before "group theory"?

 * Rings and fields will be touched upon briefly in polys and number theory, while a more indepth discussion will be in the rings, fields and modules section. Groups are a little more distanced from these, but I think I'll take your suggestion and move that section down :) Dysprosia 23:14, 6 Nov 2003 (UTC)

I am curious as to the inclusion of Set Theory in Discrete mathematics - especially since there is already a distinct Set Theory book (although there is almost nothing in it). Surely discrete mathematics is concerned almost exclusively with finite or possible countable sets, and a full treatment of set theory is not appropriate here. Would it not be more sensible to merge these, and have one book on set theory, covering both naive and axiomatic set theory? J Bytheway 23:08, 8 Feb 2005 (UTC)

 * If there is nothing in Set Theory, it should be redirected to the book here. Our efforts should be unified. Dysprosia 10:56, 9 Feb 2005 (UTC)

Split
Why split the book up? How is one to find general topics on discrete math?

Oh my gosh! I saw the word "split" and thought of a made up step in induction called "split" when I was first taught it! Speaking of which, should I add recursion and induction as sections too?

BTW, to kinda answer your question, this is wikibooks, an in-depth look at discrete etc. If you want a general overview look at the main wikipedia page. Cammy169 (discuss • contribs) 16:16, 24 April 2014 (UTC)

feedback
this is very well written and easy to understand, thanks. Please finish the book, if you have the time for it.
 * Seconded. It Is Me Here  t / c 09:55, 18 April 2013 (UTC)

title: Talk:Discrete Mathematics


text:
German/Appendices/Grammar I

Beginning German | Basic German | Intermediate German

Nominative case personal pronouns
The nominative case is used as the subject of a verb.

Genitive case personal pronouns
The genitive case corresponds to the possessive case in English or to the English objective case preceded by 'of' and denoting possession. The use of genitive personal pronouns is very rare in German and many Germans are unable to use them correctly.

Examples:
 * Ich erbarme mich eurer. ~           I take pity on you(rs).
 * meiner unbedeutenden Meinung nach. ~ in my humble opinion (IMHO)

Dative case personal pronouns
The personal pronouns in the dative case are used as indirect objects of verbs and after the prepositions aus, außer, bei, mit, nach, seit, von, zu.

Accusative case personal pronouns
The personal pronouns in the accusative case are used as direct objects of transitve verbs and after the prepositions durch, für, gegen, ohne, um.

title: German/Appendices/Grammar I


text:
Physics Study Guide/Standing waves

=Standing waves=

Wave speed is equal to the square root of tension divided by the linear density of the string.

Linear density of the string is equal to the mass divided by the length of the string.

The fundamental wavelength is equal to two times the length of the string.

Variables

Definition of terms

Fundamental frequency: the frequency when the wavelength is the longest allowed, this gives us the lowest sound that we can get from the system.

In a string, the length of the string is half of the largest wavelength that can create a standing wave, called its fundamental wavelength.

title: Physics Study Guide/Standing waves


text:
Physics Study Guide/Wave overtones

=Wave overtones=

For resonance in a taut string, the first harmonic is determined for a wave form with one antinode and two nodes. That is, the two ends of the string are nodes because they do not vibrate while the middle of the string is an antinode because it experiences the greatest change in amplitude. This means that one half of a full wavelength is represented by the length of the resonating structure.

The frequency of the first harmonic is equal to wave speed divided by twice the length of the string. (Recall that wave speed is equal to wavelength times frequency.)

The wavelength of the first harmonic is equal to double the length of the string.

The "nth" wavelength is equal to the fundamental wavelength divided by n.

Harmonics for a taut string*

* or any wave system with two identical ends, such as a pipe with two open or closed ends. In the case of a pipe with two open ends, there are two antinodes at the ends of the pipe and a single node in the middle of the pipe, but the mathematics work out identically.

Definition of terms

The first overtone is the first allowed harmonic above the fundamental frequency (F1).

In the case of a system with two different ends (as in the case of a tube open at one end), the closed end is a node and the open end is an antinode. The first resonant frequency has only a quarter of a wave in the tube. This means that the first harmonic is characterized by a wavelength four times the length of the tube.

The wavelength of the first harmonic is equal to four times the length of the string.

The "nth" wavelength is equal to the fundamental wavelength divided by n.

Note that "n" must be odd in this case as only odd harmonics will resonate in this situation.

Harmonics for a system with two different ends*

* such as a pipe with one end open and one end closed †In this case only the odd harmonics resonate, so n is an odd integer.

Vs: velocity of sound
 * dependent on qualities of the medium transmitting the sound, (the air) such as its density, temperature, and “springiness.” A complicated equation, we concentrate only on temperature.
 * increases as temperature increases (molecules move faster.)
 * is higher for liquids and solids than for gasses (molecules are closer together.)
 * for “room air” is 340 meters per second (m/s).
 * Speed of sound is 343 meters per second at 20 degrees C. Based on the material sound is passing through and the temperature, the speed of sound changes.

title: Physics Study Guide/Wave overtones


text:
General Astronomy

Astronomy is the scientific study of celestial bodies in the visible universe, from the scale of a few meters to the macro scale, including: the underlying physics governing those bodies, what they are made of, their properties, distribution, relation, distance, movement, creation, age and demise.

Our understanding of the universe has dramatically improved due to the progress of technology. Astronomy has been one of the most modernized areas of scientific study, but it is also one of the oldest sciences — practiced by all ancient civilizations to some degree. Sadly, people have increasingly started to lose connection with the observable universe, something that was previously even required for measuring time, and defining seasons. Astronomy is among our species' first technological steps, but today only passingly remarked about when it verifies something thought about in theoretical physics. Even in a highly industrialized global civilization, defined by consumerism only a few of us had the chance to go beyond simple images and concepts and have in considering what is around our blue dot and its implications for us.

This Wikibook introduces the reader to that tapestry and the process that revealed it to humanity. It presents astronomy not only as a field of knowledge, but also as a human endeavor in science.

Table of Contents

 * 1) /The Modern View of the Cosmos/
 * 2) /The Big Picture/
 * 3) /Short History of the Universe/
 * 4) /Scientific Notation/
 * 5) /The Scientific Method/
 * 6) /What People do in Astronomy/
 * 7) /Current Unsolved Mysteries/
 * 8) /Observational Astronomy/
 * 9) /The Celestial Sphere/
 * 10) /Coordinate Systems/
 * 11) /Phases of the Moon/
 * 12) /Eclipses/
 * 13) /Daily Motions/
 * 14) /Yearly Motions/
 * 15) /Motion and Gravity/
 * 16) /The Early Origins of Astronomy/
 * 17) The First Physics (Aristotle)
 * 18) Difficulties in the Geocentric Model
 * 19) The Heliocentric Model (Copernicus)
 * 20) New Ideas About Motion (Galileo)
 * 21) Order in Planetary Orbits
 * 22) Principles of Light
 * 23) What is Light?
 * 24) /The Spectrum/
 * 25) /Basic Astrophysics/
 * 26) /Atomic Emission and Absorption/
 * 27) /Molecular Emission and Absorption/
 * 28) /Thermal Radiation/
 * 29) /The Doppler Effect/
 * 30) /Telescopes/
 * 31) Basic Optics
 * 32) Optical Telescopes
 * 33) Telescopes of Other Wavelengths
 * 34) Neutrino Telescopes
 * 35) Gravitational Wave Telescopes
 * 36) Other Observations
 * 37) /Planetary science/
 * 38) /The Terrestrial Planets/
 * 39) /The Jovian Planets/
 * 40) /Planetary Moons/
 * 41) /Comets/
 * 42) /Asteroids/
 * 43) /Meteors and Meteorites/
 * 44) /The Kuiper Belt/
 * 45) /Extrasolar Planets/
 * 46) /Formation of the Solar System/
 * 47) Earth as a Planet
 * 48) /Earth's Early Years/
 * 49) /Formation of the Moon/
 * 50) /The Biosphere/
 * 51) /The Atmosphere/
 * 52) /The Water Cycle/
 * 53) /Earth/
 * 54) /Earth's Moon/
 * 55) Space Exploration
 * 56) /First Steps into Space/
 * 57) /The Apollo Missions/
 * 58) /Pioneers and Voyagers/
 * 59) /The Great Observatories/
 * 60) /Major Future Missions/
 * 61) Astrobiology and Extraterrestrial Life
 * 62) /The Drake Equation/
 * 63) /Organic Chemistry for Astronomy/
 * 64) /Life in the Solar System/
 * 65) /The Search for Extraterrestrial Intelligence/
 * 66) The Sun
 * 67) /Fusion in the Sun/
 * 68) /Convective and Radiative Zones/
 * 69) /The Photosphere/
 * 70) /Solar Activity/
 * 71) /Space Weather/
 * 72) /Helioseismology/
 * 73) /The Solar Cycle/
 * 74) Stars
 * 75) /Mass/
 * 76) /Luminosity/
 * 77) /Temperature/
 * 78) The H-R Diagram
 * 79) /Star Clusters as Cosmic Laboratories/
 * 80) The Stellar Life Cycle
 * 81) /Protostars and Stellar Nurseries/
 * 82) /The Life of Low Mass Stars/
 * 83) /The Death of Low Mass Stars/
 * 84) /The Life of High Mass Stars/
 * 85) /The Death of High Mass Stars/
 * 86) Black Holes
 * 87) /Life of the Black Hole/
 * 88) /Black Holes in Hiding/
 * 89) /History of the Black Hole/
 * 90) /The Theory of the Naked Singularity/
 * 91) /Spaghettification/
 * 92) /Black Holes/Hawking Radiation/
 * 93) Galaxies
 * 94) /The Milky Way/
 * 95) /Types of Galaxies/
 * 96) /Galactic Formation/
 * 97) /Galactic Evolution/
 * 98) /Supermassive Black Holes/
 * 99) /Active Galactic Nuclei and Quasars/
 * 100) Gamma-Ray Bursts and Cosmic Rays
 * 101) /Introduction and Brief History of Gamma-Ray Bursts/
 * 102) /Long-Soft and Short-Hard Classifications/
 * 103) /Fluence and Extragalactic Nature/
 * 104) /Sources of Gamma-Ray Bursts/
 * 105) /Lingering Mysteries/
 * 106) Cosmology
 * 107) /The Distance Ladder/
 * 108) /The Big Bang and Cosmic Expansion/
 * 109) /The First Three Minutes/
 * 110) /Higgs Boson/
 * 111) /An Accelerating Universe/

 * References
 * /Exercises/

Also on Wikimedia
Wikibooks is a Web site where this and other free textbooks are developed. In addition to this book, Wikibooks is the host of related textbook projects.
 * General Relativity, an advanced undergraduate treatment of the principles of general relativity
 * Astrophysics, a textbook for beginning students in physics and astronomy
 * Astrodynamics, a look at the principles behind orbiting satellites
 * Wikijunior:Solar System, a children's nonfiction book about the Solar System
 * Messier Index, a list of all the deep-sky objects in the Messier Index.

Sterrekunde Kosmografie 天文学

title: General Astronomy


text:
General Astronomy/The Solar System

General Astronomy > The Solar System

<< Astronomy | The Sun >>

The Solar System may be broadly defined as that portion of the universe under the gravitational influence of the Sun. This includes the Sun itself as well as all planets, moons, asteroids, comets, dust, and ice orbiting the Sun.

The Solar System is an example of a star system, which is similarly defined as that portion of the universe under the gravitational influence of one or more co-orbiting stars. The Solar System is a unitary star system, as it has only one star (Sol, our Sun).

Components of the Solar System
The largest, most massive, and most prominent element of the Solar System is, of course, the Sun. The Sun makes up 99.8% of the mass of the Solar System. It is literally the point around which the entire Solar System turns. The Sun is virtually at the center of the Solar System; although gravity tugs by the planets may move the center of the System slightly away from the center of the Sun, it always resides deep within the Sun's core.

The next largest objects in the Solar System are the planets. There are generally considered to be eight planets in the Solar System. They can be divided into two types: (1) the gas giant planets, which include Jupiter, Saturn, Uranus, and Neptune and (2) the terrestrial planets Mercury, Venus, Earth, and Mars. All eight planets orbit the Sun in elliptical, roughly circular orbits, in approximately the same plane. However, no planet orbits in exactly a circular orbit or exactly in the plane of the Sun's rotation. The orbit of Jupiter is the closest to the plane and circularity; the orbit of Pluto (a dwarf planet) deviates the most from both the plane and from circularity.

After the eight major planets are the minor planets, asteroids and comets. Asteroids and comets are smaller objects than planets, but also orbit the Sun. Asteroids and comets are distinguished by their content: asteroids are primarily made up of rock, while comets are primarily made of ices and volatile compounds.

Minor planets may be found anywhere in the Solar System, in orbits varying from circular to highly elliptical. Most, however, are found in three belts. The main asteroid belt is found between the planets Mars and Jupiter. As the name implies, it is made almost entirely of asteroids. The ../Kuiper Belt/ is found outside the orbit of Neptune, and encompasses the area from 30 to 100 astronomical units from the Sun. The Kuiper belt contains mainly comets, including very large comet-like objects called cubewanos or plutinos. Some astronomers also consider Pluto to be part of the Kuiper belt. The ../Oort Cloud/ is another belt of comets, and is believed to extend out to approximately one light-year from the Sun. Its existence is deduced from the frequent visitation of long-period comets, comets with extremely elliptical or even hyperbolic orbits.

Arrangement of the Solar System
The Solar System may be divided by its components into three major regions: the inner system, the near outer system, and the far outer system. The near outer system might also be referred to as the middle system. The general term outer system refers to both the near and far outer systems.

The inner system is composed of the Sun (the largest mass), the terrestrial planets (rocky and closer to the sun) and their moons(moons are drawn to planets because of their gravitational force), close-orbiting asteroids and comets, and the main asteroid belt. Objects in the inner system are almost exclusively composed of rock, with either no atmosphere or an atmosphere that composes little of the object's mass. The inner system's boundary is defined by the main asteroid belt, which separates it from the near outer system.

The near outer system is composed of the gas giant planets and their moons, and asteroids and comets that orbit between the main asteroid belt and the Kuiper belt. Objects in the near outer system may have rock, liquid, gas, and ice as significant components. The near outer system's boundary is defined by the orbit of Neptune.

The far outer system is composed of the ice planet Pluto, the Kuiper belt, the Oort Cloud, and comets that orbit between the belt and the cloud. Objects in the far outer system may have some rock components, but are mainly composed of ices.

Boundary of the Solar System
The boundary of the Solar System is defined in two ways. The gravitational boundary may be described as the point at which objects no longer orbit the Sun. This boundary includes the Oort Cloud, but is poorly defined, as an object is not compelled to orbit the Sun at any point. Another definition is to declare the heliopause as the boundary of the Solar System. This boundary is more easily detectable and definable, but resides well within the Oort Cloud.

 * 1) ../The Sun/
 * 2) ../The Planets/
 * 3) ../Asteroids and Comets/
 * 4) ../History of the Solar System/

<< Astronomy | The Solar System | The Sun >> | Stars, Clusters and Nebulae >>

title: General Astronomy/The Solar System


text:
German/Appendices/Resources

Appendix 3 ~ Online Resources for German Language Students

Lists and directories to online resources

 * bab.la - Language Portal | Online Quizzes | Learn Languages
 * German Flashcards - Flashcards with audiofiles and dictionary
 * www.deutschlern.net - E-learning platform for beginning, intermediate and advanced students and teachers of German. Exercises based on authentic texts train reading comprehension, vocabulary, and grammar. Monitor function for teachers. Free of charge, requires free login.
 * Learn German Online - Free German lessons online.
 * Learn German for free - Free German language lessons.
 * Deutsch als Fremdsprache - Useful links for German language learners. Site in German.
 * German Language and Culture Resources - Materials and resources for learning the German language and about German-speaking culture.
 * Free Online German Tutorial - at ielanguages.com
 * Free resources for language students - Practice speaking German with audio forums.
 * Learn-German - Learn German quickly with our German tips, advice, and links.
 * Mango - Mango Languages has free German Lessons for English speakers.
 * lernsoware.de Wiki German lessons online

Über die deutsche Sprache - about German

 * Ethnologue report for German
 * Verein Deutsche Sprache

Online Wörterbücher - Dictionary

 * Free Online Dictionary - Languages of the world

Deutsch-Englisch (German-English)

 * Wiktionary - English
 * Wiktionary - German
 * bab.la German-English - Translations, synonyms, grammar, voice output, regional and colloquial expressions.
 * LEO - with audiofiles of most of the words and vocabulary trainer.
 * Dict.cc
 * BEOLINGUS
 * Langenscheidt
 * Pons - Dictionary with vocabulary trainer.
 * Ding - Ding is a Dictionary lookup program for the X window system (Linux, Unix - not for Mac or MS Windows). It comes with a German-English Dictionary with approximately 180,000 entries.r.

Nur Deutsch - German only

 * Duden
 * Deutscher Wortschatz
 * DWDS- Das digitale Wörterbuch der deutschen Sprache - German only dictionary for advanced learners.
 * Wissen.de - Orthography and foreign words
 * Redensartenindex - German idioms and proverbs with explanations

Slideshows with pictures and pronunciations
Language courses German at the time of insertion there is only one file about fruit - I will try to add new ones every week-end.

Deutsche Grammatik und Rechtschreibung- German Grammar and Spelling

 * Canoo - extensive database about inflection and word formation
 * German Grammar Resource - Free German grammar lessons
 * Free online German course - new orthography, grammar, exercises, tests, example sentences, jokes, learning tips

Aussprache - Pronunciation

 * A Guide to German Pronunciation - Pronunciation course for beginners.

Blogs

 * Deutschlernblog Tips for learning German. Site entirely in German.
 * DaF-Blog On German language and how to learn it. Parts of the Site are in English, but most of it in German.
 * Deutsch-Happen small, bite-sized snaps of German language for the advancing learner

from learners

 * Speaken Sie Deutsch?: Podcast from Canadian Hugh Gordon (Rss-Feed).

for learners

 * Guter Umgang: German language learning blog about colloquial German (RSS-Feed).
 * Let's speak German: Jokes, poems, tonguetwisters and more in German (RSS-Feed).
 * Podcasts of Deutsche Welle: Nachrichten, Top-Thema, Stichwort, Sprachbar and Alltagsdeutsch are specifically made for language learners. Most of the texts can be found on the pages Deutsch im Fokus (Sprachbar, Stichwort and Alltagsdeutsch) and Didaktuelles (Nachrichten and Top-Thema).
 * DW: Slowly spoken news - suitable for B2, C1
 * Slow German: Podcast in slowly spoken German across a variety of topics, ranging from absolute beginner to intermediate.

Tandem
Tandem by E-Mail

The Mixxer Tandem via Skype

title: German/Appendices/Resources


text:
Windows Programming

Introduction
This book aims to be a comprehensive source for any developer who is interested in programming for the Windows platform. It starts at the lowest level, with the Win32 API (C and VB Classic) and then goes over to MFC (C++). Beyond these basic sections, it will cover COM, and the creation of ActiveX modules from a variety of languages. Next, it delves into the Windows DDK, and talk about programming device drivers for Windows platform. Finally, it moves on to the highest-level programming tasks, including shell extensions, shell scripting, and finally ASP and WSH.

Other topics that will be discussed here are: Writing screen-savers, creating HTML help modules, and compiling DLL files.

This book will focus on topics that are specific to Windows, and avoids general programming topics. For related material the reader is encouraged to look into Wikibooks other works, they will cover general programming, ASM, C, C++, Visual Basic and Visual Basic.NET and other languages and concepts in greater detail. Appropriate links to these books are provided.

The reader is assumed to have a previous knowledge of the programming languages involved. Specifically, prior knowledge in C, C++, and Visual Basic is required for certain sections of this book.

Section 1: Windows Basics

 * Windows System Architecture
 * User Mode vs Kernel Mode
 * C and Win32 API
 *
 * Handles and Data Types
 * Unicode
 * Dynamic Link Libraries (DLL)
 * Programming Windows With OSS Tools
 * Resource Scripts

Section 2: Win32 API and UI Controls

 * Message Loop Architecture
 * Interfacing (Mouse, keyboard, and timer messages)
 * Window Creation
 * User Interface Controls
 * GDI and Drawing
 * Dialog Boxes
 * Input-Output
 * File Management
 * Memory Subsystem (heaps, virtual memory)
 * Multitasking
 * Interprocess Communication
 * MDI Programs
 * Registry API
 * Security API
 * Winsock

Section 3: Microsoft Foundation Classes (MFC)

 * Microsoft Foundation Classes (MFC)
 * Classes Hierarchy

Section 4: Dynamic Data Exchange (DDE), ActiveX and COM

 * Dynamic Data Exchange (DDE)
 * COM and ActiveX
 * COM Programming
 * DCOM and COM+
 * Multi-language programming examples
 * OLE Programming

Section 5: Device Driver Programming

 * Device Driver Introduction
 * The DDK
 * Driver Structure
 * Driver API
 * Terminate and Stay Resident (TSR)
 * Virtual Device Drivers (VXD)
 * Windows Driver Model (WDM)
 * Vista Driver Migration

Section 6: Shell Programming

 * Programming Shell Extensions
 * Extending IE
 * Programming Screen-savers
 * Programming Services
 * Programming CMD aka Windows Batch Programming
 * Sample FTP script
 * Control Panel Applets
 * Windows Script Host
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External Resources

 * Advanced Win32 API Newsgroup
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 * Petzold, Charles, "Programming Windows", Microsoft Press
 * Hart, Johnathan, "Windows System Programming", second edition, 2001. ISBN 0201703106
 * Gordon, Alan, "The COM and COM+ Programming Primer", 2000, ISBN 0130850322
 * Oney, Walter, "Programming the Windows Driver Model", second edition, 2002. ISBN 0735618038

title: Windows Programming


text:
Physics Study Guide/Vectors and scalars

Vectors are quantities that are characterized by having both a numerical quantity (called the "magnitude" and denoted as |v|) and a direction. Velocity is an example of a vector; it describes the time rated change in position with a numerical quantity (meters per second) as well as indicating the direction of movement.

The definition of a vector is any quantity that adds according to the parallelogram law (there are some physical quantities that have magnitude and direction that are not vectors).

Scalars are quantities in physics that have no direction. Mass is a scalar; it can describe the quantity of matter with units (kilograms) but does not describe any direction.

Multiplying vectors and scalars

 * A scalar times a scalar gives a scalar result.
 * A vector scalar-multiplied by a vector gives a scalar result (called the dot-product).
 * A vector cross-multiplied by a vector gives a vector result (called the cross-product).
 * A vector times a scalar gives a vector result.

When are scalar and vector compositions essentially the same?
Answer: when multiple vectors are in same direction then we can just add the magnitudes.so, the scalar and vector composition will be same as we do not add the directions.

What is a "dot-product"? (work when force not parallel to displacement)
Answer: Let's take gravity as our force. If you jump out of an airplane and fall you will pick up speed. (for simplicity's sake, let's ignore air drag). To work out the kinetic energy at any point you simply multiply the value of the force caused by gravity by the distance moved in the direction of the force. For example, a 180 N boy falling a distance of 10 m will have 1800 J of extra kinetic energy. We say that the man has had 1800 J of work done on him by the force of gravity.

Notice that energy is not a vector. It has a value but no direction. Gravity and displacement are vectors. They have a value plus a direction. (In this case, their directions are down and down respectively) The reason we can get a scalar energy from vectors gravity and displacement is because, in this case, they happen to point in the same direction. Gravity acts downwards and displacement is also downwards.

When two vectors point in the same direction, you can get the scalar product by just multiplying the value of the two vectors together and ignoring the direction.

But what happens if they don't point in the same direction?

Consider a man walking up a hill. Obviously it takes energy to do this because you are going against the force of gravity. The steeper the hill, the more energy it takes every step to climb it. This is something we all know unless we live on a salt lake.

In a situation like this we can still work out the work done. In the diagram, the green lines represent the displacement. To find out how much work against gravity the man does, we work out the projection of the displacement along the line of action of the force of gravity. In this case it's just the y component of the man's displacement. This is where the cos θ comes in. θ is merely the angle between the velocity vector and the force vector.

If the two forces do not point in the same direction, you can still get the scalar product by multiplying the projection of one force in the direction of the other force. Thus:

There is another method of defining the dot product which relies on components.

What is a "cross-product"? (Force on a charged particle in a magnetic field)
Answer: Suppose there is a charged particle moving in a constant magnetic field. According to the laws of electromagnetism, the particle is acted upon by a force called the Lorentz force. If this particle is moving from left to right at 30 m/s and the field is 30 Tesla pointing straight down perpendicular to the particle, the particle will actually curve in a circle spiraling out of the plane of the two with an acceleration of its charge in coulombs times 900 newtons per coulomb! This is because the calculation of the Lorentz force involves a cross-product.when cross product can replace the sin0 can take place during multiplication. A cross product can be calculated simply using the angle between the two vectors and your right hand. If the forces point parallel or 180° from each other, it's simple: the cross-product does not exist. If they are exactly perpendicular, the cross-product has a magnitude of the product of the two magnitudes. For all others in between however, the following formula is used:

But if the result is a vector, then what is the direction? That too is fairly simple, utilizing a method called the "right-hand rule".

The right-hand rule works as follows: Place your right-hand flat along the first of the two vectors with the palm facing the second vector and your thumb sticking out perpendicular to your hand. Then proceed to curl your hand towards the second vector. The direction that your thumb points is the direction that cross-product vector points! Though this definition is easy to explain visually it is slightly more complicated to calculate than the dot product.

How to draw vectors that are in or out of the plane of the page (or board)
Answer: Vectors in the plane of the page are drawn as arrows on the page. A vector that goes into the plane of the screen is typically drawn as circles with an inscribed X. A vector that comes out of the plane of the screen is typically drawn as circles with dots at their centers. The X is meant to represent the fletching on the back of an arrow or dart while the dot is meant to represent the tip of the arrow.

title: Physics Study Guide/Vectors and scalars


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File:Indonesian-alphabet-a-m.ogg

Indonesian alphabet (a-m)

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File:Indonesian-akhir.ogg

Indonesian sound for the word "akhir" (end)

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