text: User talk:Moyameehaa

title: User talk:Moyameehaa


text: User talk:Socorsan

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

title: User talk:Socorsan


text: User talk:Rekhabiju

title: User talk:Rekhabiju


text:
User talk:Jkviscon~enwikiversity

Your account will be renamed
Hello,

The developer team at Wikimedia is making some changes to how accounts work, as part of our on-going efforts to provide new and better tools for our users like cross-wiki notifications. These changes will mean you have the same account name everywhere. This will let us give you new features that will help you edit and discuss better, and allow more flexible user permissions for tools. One of the side-effects of this is that user accounts will now have to be unique across all 900 Wikimedia wikis. See the announcement for more information.

Unfortunately, your account clashes with another account also called Jkviscon. To make sure that both of you can use all Wikimedia projects in future, we have reserved the name Jkviscon~enwikiversity that only you will have. If you like it, you don't have to do anything. If you do not like it, you can pick out a different name.

Your account will still work as before, and you will be credited for all your edits made so far, but you will have to use the new account name when you log in.

Sorry for the inconvenience.

Yours, Keegan Peterzell Community Liaison, Wikimedia Foundation 23:35, 17 March 2015 (UTC)

Renamed
 This account has been renamed as part of single-user login finalisation. If you own this account you can |log in using your previous username and password for more information. If you do not like this account's new name, you can choose your own using this form after logging in: . -- Keegan (WMF) (talk) 06:12, 19 April 2015 (UTC)

title: User talk:Jkviscon~enwikiversity


text: User talk:T-Bee

title: User talk:T-Bee


text:
User talk:Volkn~enwikiversity

Your account will be renamed
Hello,

The developer team at Wikimedia is making some changes to how accounts work, as part of our on-going efforts to provide new and better tools for our users like cross-wiki notifications. These changes will mean you have the same account name everywhere. This will let us give you new features that will help you edit and discuss better, and allow more flexible user permissions for tools. One of the side-effects of this is that user accounts will now have to be unique across all 900 Wikimedia wikis. See the announcement for more information.

Unfortunately, your account clashes with another account also called Volkn. To make sure that both of you can use all Wikimedia projects in future, we have reserved the name Volkn~enwikiversity that only you will have. If you like it, you don't have to do anything. If you do not like it, you can pick out a different name.

Your account will still work as before, and you will be credited for all your edits made so far, but you will have to use the new account name when you log in.

Sorry for the inconvenience.

Yours, Keegan Peterzell Community Liaison, Wikimedia Foundation 23:46, 17 March 2015 (UTC)

Renamed
 This account has been renamed as part of single-user login finalisation. If you own this account you can |log in using your previous username and password for more information. If you do not like this account's new name, you can choose your own using this form after logging in: . -- Keegan (WMF) (talk) 06:24, 19 April 2015 (UTC)

title: User talk:Volkn~enwikiversity


text: User talk:Sivakumar

title: User talk:Sivakumar


text:
User talk:Randomize~enwikiversity

Your account will be renamed
Hello,

The developer team at Wikimedia is making some changes to how accounts work, as part of our on-going efforts to provide new and better tools for our users like cross-wiki notifications. These changes will mean you have the same account name everywhere. This will let us give you new features that will help you edit and discuss better, and allow more flexible user permissions for tools. One of the side-effects of this is that user accounts will now have to be unique across all 900 Wikimedia wikis. See the announcement for more information.

Unfortunately, your account clashes with another account also called Randomize. To make sure that both of you can use all Wikimedia projects in future, we have reserved the name Randomize~enwikiversity that only you will have. If you like it, you don't have to do anything. If you do not like it, you can pick out a different name.

Your account will still work as before, and you will be credited for all your edits made so far, but you will have to use the new account name when you log in.

Sorry for the inconvenience.

Yours, Keegan Peterzell Community Liaison, Wikimedia Foundation 23:41, 17 March 2015 (UTC)

Renamed
 This account has been renamed as part of single-user login finalisation. If you own this account you can |log in using your previous username and password for more information. If you do not like this account's new name, you can choose your own using this form after logging in: . -- Keegan (WMF) (talk) 06:18, 19 April 2015 (UTC)

title: User talk:Randomize~enwikiversity


text:
User talk:Tencho1023~enwikiversity

Your account will be renamed
Hello,

The developer team at Wikimedia is making some changes to how accounts work, as part of our on-going efforts to provide new and better tools for our users like cross-wiki notifications. These changes will mean you have the same account name everywhere. This will let us give you new features that will help you edit and discuss better, and allow more flexible user permissions for tools. One of the side-effects of this is that user accounts will now have to be unique across all 900 Wikimedia wikis. See the announcement for more information.

Unfortunately, your account clashes with another account also called Tencho1023. To make sure that both of you can use all Wikimedia projects in future, we have reserved the name Tencho1023~enwikiversity that only you will have. If you like it, you don't have to do anything. If you do not like it, you can pick out a different name.

Your account will still work as before, and you will be credited for all your edits made so far, but you will have to use the new account name when you log in.

Sorry for the inconvenience.

Yours, Keegan Peterzell Community Liaison, Wikimedia Foundation 23:45, 17 March 2015 (UTC)

Renamed
 This account has been renamed as part of single-user login finalisation. If you own this account you can |log in using your previous username and password for more information. If you do not like this account's new name, you can choose your own using this form after logging in: . -- Keegan (WMF) (talk) 06:24, 19 April 2015 (UTC)

title: User talk:Tencho1023~enwikiversity


text: User talk:EncycloPetey

title: User talk:EncycloPetey


text: User talk:Mattwj2002

title: User talk:Mattwj2002


text: User talk:Greencypress

title: User talk:Greencypress


text:
User talk:Michel~enwikiversity

Your account will be renamed
Hello,

The developer team at Wikimedia is making some changes to how accounts work, as part of our on-going efforts to provide new and better tools for our users like cross-wiki notifications. These changes will mean you have the same account name everywhere. This will let us give you new features that will help you edit and discuss better, and allow more flexible user permissions for tools. One of the side-effects of this is that user accounts will now have to be unique across all 900 Wikimedia wikis. See the announcement for more information.

Unfortunately, your account clashes with another account also called Michel. To make sure that both of you can use all Wikimedia projects in future, we have reserved the name Michel~enwikiversity that only you will have. If you like it, you don't have to do anything. If you do not like it, you can pick out a different name.

Your account will still work as before, and you will be credited for all your edits made so far, but you will have to use the new account name when you log in.

Sorry for the inconvenience.

Yours, Keegan Peterzell Community Liaison, Wikimedia Foundation 23:43, 17 March 2015 (UTC)

Renamed
 This account has been renamed as part of single-user login finalisation. If you own this account you can |log in using your previous username and password for more information. If you do not like this account's new name, you can choose your own using this form after logging in: . -- Keegan (WMF) (talk) 06:15, 19 April 2015 (UTC)

title: User talk:Michel~enwikiversity


text: User talk:Stephen901

title: User talk:Stephen901


text: User talk:Jpm2112

title: User talk:Jpm2112


text:
User talk:Srinivasasha

Learning to learn a wiki way
Hi Srinivasasha, I should have taken your advice first and searched for similar articles. Any way now I've found you I'd like to invite you to join the Learning to learn a wiki way project. It covers a similar area to your How to start a Learning project it would be good to get your input on this subject. Mystictim 20:19, 29 November 2006 (UTC)

title: User talk:Srinivasasha


text: User talk:Cooluv2k3

title: User talk:Cooluv2k3


text: User talk:Millsdavid

title: User talk:Millsdavid


text:
Template:Disclosures/POV

This page is part of Template:Disclosures

title: Template:Disclosures/POV


text:
Template:Disclosures/EP

|

This page is part of Template:Disclosures

title: Template:Disclosures/EP


text:
High school physics

Fundamental Concepts

 * /Introduction/
 * /Basics/
 * Scientific Method (also Experiment, Observation and Testing Hypotheses)
 * Units and dimensions/Dimensional Analysis
 * Metric system
 * Precision, Accuracy, Rounding, and Significant figures
 * Scientific notation
 * Trigonometry
 * Vectors

Mechanics

 * Motion - Mechanics
 * Motion - Kinematics
 * Motion - Dynamics
 * Energy

Translational Motion

 * Motion in a straight line
 * Newton's Laws of Motion
 * Work, Power, and Energy
 * Gravity
 * Motion in two dimensions

Rotational Motion

 * Circular Motion
 * Angular Velocity
 * Centripetal acceleration
 * Center of mass
 * Torque and Angular Acceleration
 * Moment of Inertia

Fluid Mechanics

 * Hydrostatics: Fluids at Rest
 * Hydrodynamics: Fluids in Motion

Thermodynamics

 * Basic Definitions
 * Zeroth Law of Thermodynamics
 * First Law of Thermodynamics
 * Second Law of Thermodynamics
 * Third Law of Thermodynamics

Electricity and Magnetism

 * Electric charge
 * Coulomb's Law
 * /Electric Fields/ and Forces
 * Electric Circuits
 * Electric flux and Gauss's law
 * Magnetic Fields and Forces
 * Electromagnets
 * Permanent Magnets
 * Magnetism
 * Kirchhoff's current law, and Kirchhoff's loop law

Oscillations and Waves

 * Simple Harmonic Motion
 * Pendulums
 * Waves
 * Sound
 * Light and Optics

Atomic, Nuclear, and Particle Physics

 * The Atom
 * Basic atomic physics
 * Particle Physics

Advanced Topics for Exploration

 * Special Relativity
 * General Relativity
 * Cosmology
 * Quantum Mechanics

Physics Study Guide
Also look at the Physics Study Guide

ja:Topic:高校の物理学 pt:Portal:Formação Intermediária/Física

title: High school physics


text:
Draft:Original research/Classical mechanics

In physics relating to or based upon concepts and theories that preceded the theories of relativity and quantum mechanics; such as Newtonian physics are called classical. Usually, in other fields, classical refers to the classical history period which dates from around 2,000 to 1,000 b2k.

Introduction
Classical mechanics is the study of everyday forces which we come in contact with. The goal of classical physics is to be able to describe perfectly any and all kinds of motion. From this it would follow that if you knew only part of the motion of an object, then you could determine each other part of the motion.

Theoretical classical mechanics
Def. an "[amount of] intervening space between two points, usually geographical points, usually (but not necessarily) measured along a straight line" is called a distance.

Def. the "inevitable progression into the future with the passing of present events into the past" or the "inevitable passing of events from future to present then past" is called time.

Def. the "quantity of matter which a body contains, irrespective of its bulk or volume" or a "quantity of matter cohering together so as to make one body, or an aggregation of particles or things which collectively make one body or quantity" is called a mass.

Def. the "rate of motion or action, specifically the magnitude of the velocity; the rate distance is traversed in a given time" is called the speed.

Positions
In pre-Einstein relativity (known as Galilean relativity), time is considered an absolute, i.e., the time interval that is observed to elapse between any given pair of events is the same for all observers.

In addition to relying on absolute time, classical mechanics assumes Euclidean geometry for the structure of space.

Motions
Essentially, motion boils down to where an object is, how fast it is going, and how fast it is changing how fast it is going.

In strict physical terms, these quantities are:

Position: the location of an object (generally from its centre of gravity) in relation to all other objects in a system.

Velocity: the rate at which the position changes.

Acceleration: The rate at which the object's velocity changes.

The units used to describe these quantities are:

 * meter (m): the standard unit for distance in one direction. A meter is about 39 inches, or slightly more the three feet.
 * second (s): the standard unit for time. a second is the time that elapses during 9,192,631,770 vibrations of the cesium 133 atom.

These relate to each other as follows:

Position = x (in meters)

Speeds and velocity
Velocity = change in position (distance d) divided by change in time (t)

 * $$\mathbf{v} = {\mathrm{d}\mathbf{r} \over \mathrm{d}t}\,\!$$.

The velocity of the first object as seen by the second object is
 * $$\mathbf{u}' = \mathbf{u} - \mathbf{v} \, .$$

Similarly, the first object sees the velocity of the second object as
 * $$\mathbf{v'}= \mathbf{v} - \mathbf{u} \, .$$

When both objects are moving in the same direction, this equation can be simplified to
 * $$\mathbf{u}' = ( u - v ) \mathbf{d} \, .$$

Or, by ignoring direction, the difference can be given in terms of speed only:
 * $$u' = u - v \, .$$

Accelerations
Acceleration = change in velocity (v) divided by change in time

 * a = (change in v)/t

for example, if I were to walk in a straight line 10 m, and it took me 5 s to do this, my velocity would be:

 * v = (change in d)/t
 * v = 10 m/5 s
 * v = 2 m/s

my velocity was 2 m/s

In a similar fashion, if you knew my initial velocity to be 2 m/s and after a 20 s stretch, my velocity was 42 m/s, my acceleration would be

 * a = (change in v)/t
 * a = (42 m/s - 2 m/s)/20 s
 * a = (40 m/s)/20 s
 * a = 2 m/s²

my acceleration was 2 m/s²

Reference frames
Consider two reference frames S and S'. For observers in each of the reference frames an event has space-time coordinates of (x,y,z,t) in frame S and ( x', y' , z' , t' ) in frame S'. Assuming time is measured the same in all reference frames, and if we require when, then the relation between the space-time coordinates of the same event observed from the reference frames S' and S, which are moving at a relative velocity of u in the x direction is:
 * $$x' = x - u t \,$$
 * $$y' = y \,$$
 * $$z' = z \,$$
 * $$t' = t \, .$$

Spectra of motions
In physics, there is a distinction between average velocity and instantaneous velocity. Instantaneous velocity is the velocity at a specific point in time, and can be only derived with advanced calculus which may be covered in an advanced section. Average velocity, however, is what we will be dealing with. Average velocity involves the difference between two points in space and the difference in time associated with them. This is different from average speed. Average speed is the distance traveled divided by the time expended. Speed is based on the path an object takes, while velocity is based on the displacement of an object, i.e. the amount of distance it actually covered. for example, if I were to move 10 m to the left, and then 10 m to the right, over the course of 1 s, my path would be 20 m long, but my displacement would be 0 m, because the starting point and ending point were the same. Therefore, my average speed would be 20 m/s, while my velocity would be 0 m/s. The difference is important, because in physics, speed is never used, only velocity. The reason for this is that a physicist is considered an outside observer, and should be able to describe the event perfectly without actually witnessing what occurred. If only two data points are taken, then velocity is the only way to calculate things because no data has been taken in the middle, and no data about the path can be known.

Masses
Long ago, in the 1600's, a man named Isaac Newton established three laws relating to motion, which brought physics out of what was described above to a new level.

His first law was that each object will stay in motion unless acted upon by an unbalanced outside force, and likewise for an object at rest. This established a thing called momentum, which is a property of matter based upon an object's mass and velocity. An object, like a train moving at 10 m/s, will have more momentum than, say, a pea at the same velocity. This means that, in the same amount of time, the train will require more energy to stop than the pea. However, velocity also plays a role, as a 20 m/s train will be harder to stop than a 10 m/s train.

Forces
His second law stated that force equals mass multiplied by acceleration. Derivation of F = ma from Newton's original definition (Force is the rate of change of momentum)

$$ F=\frac{dp}{dt} = \frac{d(mv)}{dt} =m\frac{dv}{dt} + \frac{dm}{dt}v = ma + \frac{dm}{dt}v$$

Then, if mass is kept constant, $$\frac{dm}{dt}=0$$, and $$F=ma \,$$.

Newton's Laws
Classical Mechanics is the study of the motion of particles and systems of particles and of the forces which induce changes in motion. Quantum mechanics and Relativity, developed in the 20th century, were advancements, which corrected classical mechanical errors in motion. However, since classical mechanics is easier to understand and widely applicable to most everyday physical situations it is still quite useful today.

Classical Mechanics were described in detail by Sir Isaac Newton in his two volume Philosophiae Naturalis Principia Mathematica in the 17th century, sometimes referred to as Principia or Principia Mathematica. We will begin our study of classical mechanics with Newton's three laws of motion.

1) An object at rest will remain at rest unless acted upon by an external force.  An object in motion will move at a constant velocity unless acted upon by an external force.

This first law was a major advancement in physics, as it was previously assumed that an object in motion on earth would always return to a state of rest unless acted on by a force. We now understand that the force of friction must act upon the object to return it to rest.

2) Force = the change in momentum of a particle (or system of particles) with respect to time.

This law is often portrayed in the simple equation,

$$F=ma$$

which is true when the mass is constant. A derivation of this simpler equation is displayed below.

3) Every action has an equal and opposite action.

This can be displayed by pushing on the wall or firing a gun. When I apply a force to the wall, the wall in turn applies an equal and opposite force on me. When the propellant in a gun is ignited the resulting chamber pressure propels the bullet forward and an equal force pushes the gun backward, providing the kickback force.


text:
User:Billcr

Useful Links

 * All templates
 * Parser functions
 * Magic words
 * Special:Prefixindex

My stuff

 * My sandbox

title: User:Billcr


text:
Wikiversity:Page protection templates

There are several reasons why Wikiversity participants might want to protect some pages from editing. Wikiversity does not prevent participants from crossing the line into original research and since Wikiversity participants are also encouraged to document their personal learning experiences, page protection at Wikiversity is slightly more complex than at Wikipedia. Wikiversity incorporates the page protection system of Wikipedia (protection of pages from editing by custodians), but adds an additional element. Registered Wikiversity participants can protect pages that they create from modification by other Wikiversity editors. This allows Wikiversity participants to easily create "archive pages" that will document their own experiences, thoughts, plans and multiple stable versions of documents set aside for study and future reference. Courses and research projects that are in progress can be restricted so that only some Wikiversity participants can edit them.

Decisions by Wikipedia users to protect pages are always subject to review and reversal by custodians and referees. Pages that a user has created can be marked as protected using the page protection templates.

These templates do not provide a software block against other users from editing a page. They function by trust and respect (which are made easier by technical functions of the mediawiki software).

Protected course template
Template:Protected course

One reason to protect pages from editing is if a main namespace page is being used by participants in a course at a bricks-and-mortar educational institution. You can use Template:Protected course to restrict editing of a page for a course to just people enrolled in that course.

Example: see UIUC PHIL 270.

Protect template
Template:Protect can be used to request others not to edit a research project.

produces:

Only Wikiversity participants with a registered username and a confirmed email address can use this page protection template. Anyone using this page protection template must place the scholarly ethics template on their user page.

The first section of a page using Template:Protect must explain why the page has been protected from editing.

Any Wikiversity editor can remove this page protection template from a page if
 * the page is not in the main namespace
 * the template was placed on the page by someone who was not the creator of the page
 * there is no reason provided for use of the template
 * the person who placed the template on the page is not a registered user, does not have a confirmed email address, or does not have the scholarly ethics template an their user page.

Wikiversity referees and custodians can remove a page protection template from a page if the page has content that is against Wikiversity policy or is disruptive to Wikiversity.

Protected data template
Some pages might contain raw data or machine-readable data to accompany a lesson. Any small change to this data could prevent it from being used properly. The template could be used on these pages, it produces:

title: Wikiversity:Page protection templates


text: Template:For

title: Template:For


text: Template:For/aux

title: Template:For/aux


text:
Template talk:For

See m:Template talk:For

title: Template talk:For


text:
Wikiversity:Stub

Stubs are Wikiversity resources with clear educational objectives and learning goals which require further development for participants to achieve learning outcomes. Stubs are valuable first steps towards mature resources. A great stub aims to create interest in the topic and helps others understand how they can assist with the educational objectives and learning goals. However, before beginning a new stub, consider whether you can integrate what you wish to do into an existing learning project, develop the resource within your userspace until participants can learn from it, or whether a carefully targeted redirect is a more appropriate option. Stubs which are difficult to develop further are likely to be deleted.

Desirable characteristics of a stub
If you create a stubby resource, please include:

 * stub or a related template as found at Category:Stub templates,
 * Some associations with Wikiversity Schools and Portals,
 * At least one link to a relevant article at Wikipedia, book at Wikibooks, or an external source,
 * Some relevant categories,
 * At least one paragraph explaining concisely what objectives you hope to accomplish, and
 * At least one paragraph explaining concisely what knowledge or skills participants will hopefully gain

Examples of stubs

 * Molecular Biology began as a page with only placeholder content sections. A page with a hierarchial structure encourages relevant edits such as these:.
 * Calculus pre-test contains general information organized to appeal to a broad audience. Note how this lead to a small discussion about how to develop the page further.

Other templates
Other templates which mark pages as stubs are:

 * - adds pages to Category:Stub pages
 * - adds pages to Category:Empty pages
 * - adds a project box stating that the page is a stub

title: Wikiversity:Stub


text:
User talk:Teskar~enwikiversity

Your account will be renamed
Hello,

The developer team at Wikimedia is making some changes to how accounts work, as part of our on-going efforts to provide new and better tools for our users like cross-wiki notifications. These changes will mean you have the same account name everywhere. This will let us give you new features that will help you edit and discuss better, and allow more flexible user permissions for tools. One of the side-effects of this is that user accounts will now have to be unique across all 900 Wikimedia wikis. See the announcement for more information.

Unfortunately, your account clashes with another account also called Teskar. To make sure that both of you can use all Wikimedia projects in future, we have reserved the name Teskar~enwikiversity that only you will have. If you like it, you don't have to do anything. If you do not like it, you can pick out a different name.

Your account will still work as before, and you will be credited for all your edits made so far, but you will have to use the new account name when you log in.

Sorry for the inconvenience.

Yours, Keegan Peterzell Community Liaison, Wikimedia Foundation 23:45, 17 March 2015 (UTC)

Renamed
 This account has been renamed as part of single-user login finalisation. If you own this account you can |log in using your previous username and password for more information. If you do not like this account's new name, you can choose your own using this form after logging in: . -- Keegan (WMF) (talk) 06:24, 19 April 2015 (UTC)

title: User talk:Teskar~enwikiversity


text:
User:TimNelson/Sig/Basic

TimNelson (Talk)

title: User:TimNelson/Sig/Basic


text: User talk:Laura Bogart

title: User talk:Laura Bogart


text:
Template:Please don't edit

User: respectfully asks that people use the |discussion page, their talk page or email them, rather than contribute to this page at this time. This page might be under construction, controversial, used currently as part of a brick and mortar class by a teacher, or document an ongoing research project. Please RESPECT their wishes by not editing this page.

Use this template to encourage people not to edit pages that you have created. However please keep in mind that this is a wiki that anyone can edit and that nobody owns any pages on Wikiversity.

Note: you must include your username in the template call. Use the template this way:

and replace "username" with your Wikiversity username. See Page protection templates for details on when and how to use this template.

title: Template:Please don't edit


text:
Category:Protect template

See Page protection templates for details about how to use these templates.

title: Category:Protect template


text:
User:TimNelson/Comment

Here's are the parameters: To start a new comment: 0
 * 1) Indent level (cm)
 * 2) Subject line
 * 3) Username (use ~ )
 * 4) Message body

title: User:TimNelson/Comment


text:
Measurement

Meaning and definition of measurement
“Whatever exists at all, exists in some amount. To know it thoroughly involves knowing its quantity as well as its quality”. Edward Thorndike (1918, p. 16)

Measurement is the process of attaching a numeric value (datum) to an aspect of a natural phenomenon, such as the volume of the milk produced by a cow, in order to be able to describe that phenomenon accurately and make comparisons to other similar phenomena, like "the crop production of the farm have had a 120% growth over the last 5 years."

To begin the process of measurement, we need to recognize the type of phenomenon, called the physical dimension, that we would like to measure. For example the diameter of the front wheel of a bicycle is of type Length, how fast the bicycle is moving is described by Speed and the amount of air crammed inside the wheel is determined by Pressure. The next thing we are going to need for doing a measurement is a Standard Unit for that type of aspect of natural phenomenon. For example, we can select a special person, like a king, and announce the length of his foot as the standard unit of length. From now on, when we are talking about the height of a sapling, we are talking of how many feet, each as long as the king's foot, do we need to cover the sapling. The number of the feet needed, which might turn out to be 7.75 and there is nothing wrong with that, is now considered the length of that thing. Congratulations! we have managed to correctly attach a numeric value (7.75) to the length of the sapling.

Now, for a more formal definition of measurement, we can refer to wikipedia, which says: "Measurement is the process of estimating the ratio of a magnitude of a quantity to a unit of the same type. A measurement is the result of such a process, expressed as the multiple of a real number and a unit, where the real number is the ratio. An example is 9 metres, which is an estimate of an object's length relative to a unit of length, one metre."

Importance of measurement
Unless we are able to measure some phenomena, we cannot say we scientifically know anything about that thing.

Measurement gives a base to understand the universe. All around us we are surrounded by various things. We might not note it but unconciously we are actually "measuring" things and understanding them one way or the other. Just imagine how a world would be without being able to measure anything. We are surrounded by Measurement.

Base Units
In Physics, we have now moved from Imperial units (pounds, yards etc), to the Metric System (metres, grams etc). However, we also use a variety of base units, and from these base units, we are able to derive some of the familiar units we know, e.g. the Newton. This range of units compile into a group known as the Le Système International d'Unités (SI). Most of the units you should recognize from your previous studies; these units are the base units in the SI system measurement:

Derived Units
With these base units, we can combine them to form derived units, such as the Newton, acceleration or speed; as an example, let us look at speed. Speed is described by the following equation:

$$Speed=\frac{Distance}{Time}$$

As you know, Distance is in Metres, and Time is in Seconds, so m divided by s obviously gives us m/s. Since this is higher physics, it needs to be put into index notation, which means that the derived unit now becomes $$ms^{-1}$$ If we write this as a non-negative power, then we get:

$$ms^{-1}=\frac{m}{s^1}$$

Now, let us use this derived unit to find another unit commonly met, Acceleration. Acceleration is the rate of change of Velocity, described by the equation:

$$Acceleration=\frac{Final~Velocity-Initial~Velocity}{Time~Taken}$$ or in symbols: $$a=\frac{v-u}{ \Delta\ t}$$

Thus, if we divide $$ms^{-1}$$ by the Time Taken (in seconds) we get $$ms^{-2}$$

Again, if we write this as a non-negative power, we get:

$$ms^{-2}=\frac{m}{s^2}$$

Homogeneity
This has shown how base units are used to form the derived units we know, the use of base units can also tell us whether an equation is Homogenous or not. Homogeneity can be used to see whether an equation is correct or not, but be warned, this does not necessarily mean that an equation is correct overall, it only says whether the base units are the same on both sides! The Speed equation is Homogenous because the product of the equation is $$ms^{-1}$$, and we divided the distance (m) by the time (s), so the base units used on one side of the equation are the same as the base units used on the other side of the equation.

Methods of Measurement
The base quantities are measured in different ways. The Kilogram is measured on scales, length is measured with a ruler, a Micrometre, Vernier Callipers, a Laser, etc. Current is measured with an Ammeter, Temperature with a thermometer, Time with a watch. The amount of substance is deduced by equations, as is Luminous Intensity.

Uncertainty
All measurements have a degree of uncertainty. This can be shown as an absolute uncertainty, or percentage uncertainty. (Percentage uncertainty) = 100 $$\times$$ (absolute uncertainty)/(measured value). The last figure in a number that is measured is called the doubtful figure.

title: Measurement


text:
Motion - Kinematics

Kinematics is the branch of mechanics concerned with the motions of objects without being concerned with the forces that cause the motion. In this latter respect it differs from dynamics, which is concerned with the forces that affect motion. There are three basic concepts in kinematics - speed, velocity and acceleration.

Speed
The speed of an object is how fast it is moving (the same as the ordinary, everyday definition). Speed in physics is defined as the rate of change of position with no respect to direction.

The standard equation for average speed is

 * $$v_{av} = \frac{\Delta s}{\Delta t}$$,

where

 * $$v_{av}\,$$ stands for average speed

 * $$\Delta s\,$$ stands for distance = Ending Position - Start Position

 * $$\Delta t\,$$ stands for time = Ending time - Beginning time

For example, if a bus takes two hours to travel 100 km, then it has an average speed of

 * $$v_{av} = \frac{100 {\rm\ km}}{2 {\rm\ hours}} = 50 {\rm\ km/h}$$

Speed is a scalar value, in comparison to velocity which is a vector

Velocity
Velocity is defined as the rate of change of position of a body in a given direction. The velocity of an object (such as a bus) is how fast it is moving in a particular direction. To specify the velocity, both a speed and a direction must be given. Continuing with the bus from the example above, if it is moving east of west, then its velocity is 50 km/h, e of w.

Acceleration
Acceleration is the rate of change of velocity. Recalling the definition of velocity, this could mean a change in speed or direction. So, if the bus goes around a curve without slowing down, still traveling at 50 km/hr, but now turning toward the south (say), then it is accelerating, even though its speed isn't changing.

Acceleration will prove to be an important topic when it comes to dynamics, which is concerned with the forces that make objects move.

Uniform motion
The simplest type of motion is where the change in distance is the same for every second; in other words the speed is constant. We call this uniform motion and its distance versus time graph looks like this:

Notice that the speed is the slope of the graph (rise/run). The graph has the same slope (steepness = rise/run) at all times - the speed is constant. When the distance at time zero is zero, the deltas (change in) may be omitted and the formula v = d/t used. This is often written as d = vt. The letter v is commonly used for speed which is the magnitude (size) of velocity.

It is useful to view this another way, as a graph of velocity versus time:

This graph is horizontal because the velocity is constant, the same at all times. Notice that the area under the graph, a rectangle, is vt which is the distance.

We have found relationships among the quantities:

 * The slope on the distance versus time graph is the velocity
 * The area under the v vs t graph is the distance
 * $$d = vt$$

The formula only applies to uniform motion, but the graphical relationships turn out to be true for all kinds of motion.

Example 1
Sound travels at a velocity of about 340 m/s in air. How far will it go in one tenth of a second?

 * Solution

\begin{align} d & = vt \\ & = 340 \times 0.1 \\ & = 34 \text{m} \end{align} $$

Example 2
Light travels at 3.0 x 10^8 m/s. How long will it take to go 10 km?

 * Solution

\begin{align} d & = vt \\ \frac{d}{v} & = t \\ \frac{10000}{300000000} & = t \\ 0.000033 & = t \end{align} $$

Example 3
Three year old Johnny takes off at 2 m/s. Five seconds later, his mom goes after him at 3 m/s. How far does Johnny get before his mother catches him?

 * Solution 1
 * It looks complicated, so let us picture it with a graph first. On this graph, the red line shows Johnny's motion and the blue line shows Mom's motion.
 * [[Image:Uniform_motion_graph_03.jpg|UniformMotionExample3]]

 * You should be able to understand why the red line is drawn where it is - it starts at distance zero at time zero, and its slope must be 2 m/s. Mom's line (blue) starts 5 s later and has a slope of 3.  The two meet at approximate time 15 s after Johnny starts, and distance 30 m.  Graphical solutions are always approximate.

 * Solution 2

Write d = vt for Johnny and again for Mom. We are interested in the time when their distances are equal. Johnny            Mom d = vt          d = vt           2t    =        3(t-5)    because Mom's running time is 5s less. 2t   =   3t - 15        math expansion 0   =   1t - 15        subtract 2t from both sides 15   =   t             add 15 to both sides In 15 seconds, Johnny goes 30 m. Mom travels for 10 seconds at 3 m/s so her d = vt = 3x10 = 30 m is the same. The exact answer is 30 meters.

Motion with constant acceleration
The next simplest type of motion is where the velocity (speed) is steadily increasing. Velocity is the slope on the distance vs time graph, so the graph must be curved upward. As time increases, the slope or velocity increases.

It is fascinating to see that the area under the velocity graph is equal to the distance in this case, too. We use the math notation A(t) to represent the area under the graph from time zero up to time t. A(t+Δt) is the area up to time t + Δt. The difference between these two areas is the blue shaded area in the diagram above: A(t+Δt) - A(t) = shaded area = v(t) x Δt This second equality is not quite right because v(t)xt is only the rectangular area, but the small triangle does not matter as we take Δt to be very small. Mathematicians say, "in the limit as Δt tends to zero."

Dividing both sides by Δt this is $$v = \frac{A \left( t+ \Delta\ t \right) -A(t)}{\Delta\ t}~=~\frac{\Delta\ A}{\Delta\ t}~=~\mbox{slope of area}$$

Velocity is the slope or rate of change of distance, and it is the rate of change of the area, so distance and the area under the velocity graph must be the same thing. It is probably more convincing to demonstrate this for yourself with some numerical data for the distance versus time. Any data will do; the relationship turns out to be true for any kind of motion.

Using the idea that distance is the area under the velocity graph, we can now find a formula for distance when the motion is accelerated.

 * Example 4:
 * A falling object accelerates at 9.81 m/s2. A stone is dropped (no initial speed) over a cliff and it takes 2s to fall, how high is the cliff?

$$ \begin{align} d & = v_i t + \tfrac{1}{2} at^2 \\ & = 0 + \tfrac{1}{2}(9.81)(2)^2 \\ & = 19.6\mbox{m} \end{align} $$
 * Solution

 * Example 5
 * If a car accelerates at 2 m/s2, how long will it take to travel 100m?

$$ \begin{align} d & = v_i t + \tfrac{1}{2} at^2 \\ & = \tfrac{1}{2} at^2 \qquad \mbox{Since initial velocity is zero} \\ 2d & = at^2 \\ \frac{2d}{a} & = t^2 \\ \sqrt{ \frac{ 2 \times 100 }{2} } & = \sqrt{ t^2 } \\ 10\mbox{s} & = t \\ \end{align} $$
 * Solution

Acceleration is defined as the rate of change of velocity, or the slope on the velocity graph. This gives us $$a = \tfrac{ \Delta v }{ \Delta t }$$ or $$\Delta v = \tfrac{ a }{ \Delta t }$$. Usually the motion begins at time zero, so Δt is the same as t, but there is often an initial velocity so $$\Delta v = v_\text{f} - v_\text{i}$$. Thus the formula can be written as $$ v_\text{f} - v_\text{i} = at $$ or most commonly as $$ v_\text{f} = v_\text{i} + at $$

 * Example 6
 * If a car moving at 12 m/s accelerates at 2 m/2 for 10 seconds while passing a truck, how fast will it be going after the 10s?

$$ \begin{align} v_\text{f} & = v_\text{i} + at \\ & = 12 + ( 2 \times 10 ) \\ & = 32 \text{m/s} \end{align} $$
 * Solution

While the formulas are most convenient for most problems, it is worth remembering the graphical relationships, which can be useful for harder problems.

 * Example 7
 * A bullet moving at 300 m/s hits a wooden block and travels 0.015 m while decelerating in the wood. Assume that the motion is approximately constant accelerated (or decelerated).  Calculate the acceleration of the bullet while stopping.

title: Motion - Kinematics


text:
Motion - Dynamics

Dynamics is the study of why things move, in contrast to kinematics, which is concerned with describing the motion of objects. An object's motion typically is described using Newton's Laws of Motion.

Newton's 1st Law of Motion
Newton's First Law is often stated: "An object at rest will tend to stay at rest, or an object in motion will tend to stay in uniform motion in a straight line unless acted on by an external unbalanced force." This means that an object must have an unbalanced force acting on it for it's motion to change.

Example 1
Consider a bus moving steadily at 100 km/h along a highway. Although we can assume that many forces are acting on the bus, such as weight (force due to gravity), air resistance and/or friction with the highway, we know via Newton's 1st Law of Motion that the sum of the forces acting on the bus is zero, as it is at a constant velocity.

Example 2
Consider a truck going 40 km/hr down a straight road (it is important that the road is straight in this example!). If a grocery bag is sitting in the passenger seat and the driver slams on the brakes, the groceries will typically fly off of the seat, into the glove compartment, or onto the floor. This is because the brakes are creating an unbalanced force slowing the truck, but not the grocery bag. But why doesn't the driver also get thrown out of their seat? The driver is (hopefully) wearing a seat belt, which is connected to the truck. The tension of the seat belt is providing a similar force to the driver.

Applications to Solving Physics Problems
In any situation which you have an object at rest or at constant velocity, you can take the sum of all forces acting on it to be zero, which is to say the net force acting on the object is zero.

See Newton's First Law in Action
A good experiment to illustrate the Newton's First Law of Motion is to put a book on a skateboard. Push or run behind the skateboard/book to accelerate them up to a good speed, then suddenly stop the skateboard, but do not touch the book. Assuming the book is not incredibly heavy, it should continue moving forward after the skateboard stops. This phenomenon can be explained using Newton's First Law.

Newton's 2nd Law of Motion
Newton's 2nd Law of Motion states:

"the rate of change of the momentum of an object is directly proportional to the resultant force acting upon it".

Written mathematically, this gives

$$F = \frac{dp}{dt}$$

this can easily be reduced to F = ma by using differentials

$$F = \frac{dp}{dt} = m\frac{dv}{dt} + v\frac{dm}{dt}$$

in a constant mass system

$$v\frac{dm}{dt} = 0$$

and so

$$F = m\frac{dv}{dt} = ma$$

as

$$a = \frac{dv}{dt}$$

Therefore, in a system of constant mass, the acceleration of an object is directly proportional to the resultant force acting upon it.

This formula is an experimental result. You can find it for yourself if you have some means of measuring acceleration, such as a tickertape timer or sonar attachment for a calculator to measure velocity continuously.

In the experiment, various forces are applied to a wheeled cart or glider on a frictionless air track. The easiest way to get a known force is to use the force of gravity on a hanging weight with a pulley to change the force from horizontal to vertical. Each 100 grams of mass has a force of gravity of about 1 Newton.

The tickertape is pulled through a timer that marks a dot on it every tenth of a second. From the distance between dots, the velocity can be calculated. From the change in velocity from one pair of dots to the next, the acceleration can be calculated. The experiment is repeated with various hanging masses causing different pulling forces and the acceleration is measured from the recorded motion. Graphing the experimental values for the applied force versus the resulting accelerations produces a straight line graph to within experimental accuracy. The slope is equal to the mass of the moving system to within experimental error. The formula for the graph is therefore F = ma. Force has units of Newtons where a Newton (N) is equal to a kg·m/s².

Example 1
A 1000 kg car accelerates at 0.5 m/s². Calculate the force that must be applied to it.

 * Solution:

\begin{align} F & = ma \\ & = 1000 \mathrm{kg} \times 0.5 \text{m/s}^2 \\ & = 500 \text{kg} \cdot \text{m/s}^2 \\ & = 500 \mathrm{N}

\end{align} $$

Example 2
A 0.085 kg bullet is fired from a rifle and emerges with a speed of 400 m/s. Assuming that the bullet has constant acceleration over the 0.5 m length of gun barrel, calculate the force on the bullet.

Solution: This is one of those tricky problems when the time is not known so we can't use a = Δv/Δt. We could sketch a v vs t graph where we know the area beneath is the distance 0.5 m:

Knowing the time for the bullet to accelerate in the rifle, we can find the acceleration and then the force:

$$ \begin{align} F & = ma \\ & = m \frac{\Delta v}{\Delta t} \\ & = 0.085 \frac{400}{0.0025} \\ & = 13600 \mathrm{N} \end{align} $$

Newton's 3rd Law of Motion
Newton's Third Law of Motion is often stated as "For every action there is an equal and opposite reaction." This means that for every force exerted, the exerter has an force of same magnitude but opposite direction from the exertee. More plainly put, if object A applies a force on object B, then B will apply an equal force on A in the opposite direction.

Example 1
Consider a car traveling. If the car accelerates due to a 500 N force on it there is another object that experiences a 500 N force in the opposite direction. In this case, it would be the road. Similarly, an aircraft accelerates because it applies a backward force on the air (via a propeller or turbine), and the air applies a forward force on the aircraft. In space, where there is no air, a rocket are typically used - it applies a backwards force on its exhaust material and the exhaust material applies a forward force on the rocket.

Often there are multiple forces involved. When a person shoots a rifle, a force is obviously applied to the bullet. It is the hot gunpowder gases that push on the bullet, and the bullet pushes back on the gases. The gases push back on the gun and the gun pushes forward on the gases. The gun pushes back on the person holding it, and the person pushes forward on the gun. You could continue this to the person pushing back on the Earth and the Earth pushing forward on the gun.

Action/Reaction Pairs
Consider the Earth and a ball. The force from the Earth on the ball, and the force from the ball on the Earth are of equal magnitude, but opposite directions.

The Earth and a ball in the air exert equal and opposite forces on each other. The Earth and ball in this situation are said to be "Action/Reaction" pairs.

However, consider a 100 kg mass sitting at rest on a table. There is a force downwards from the mass on the table (weight) and a force upwards from the table on the mass (normal force). However, weight and normal force are not Action/Reaction Pairs, as the weight is not created by the normal force. The true normal force in this example are the mass and the Earth, as the Earth is applying a gravitational force on the mass (weight) and the mass is applying the same magnitude force in a opposite direction.

Action/Reaction Pairs are handy to solving many Physics Exercises.

title: Motion - Dynamics


text:
Energy

"One day man will connect his apparatus to the very wheelwork of the universe... and the very forces that motivate the planets in their orbits and cause them to rotate will rotate his own machinery," Nikola Tesla

Definition
Energy is notoriously difficult to define. It is often defined as the ability to do work, but this is an incomplete definition. American Supreme Court Justice Potter Stewart famously said of pornography that he could not define it, "but I know it when I see it." Thus it is with energy. It is easy to recognize in most of its several forms: mechanical (including kinetic and gravitational potential), chemical, nuclear, electromagnetic (including light and other non-nuclear radiations), elastic, and thermal. The SI unit of energy is the joule, named in honor of James Prescott Joule, who discovered the equivalence of heat and mechanical energy. The joule is a derived unit, equivalent to kg•m²/s². It can also be expressed as newton-meters (Nm), but is not usually done to avoid confusion with the units of Torque (N x m) The word energy comes from the Greek words en and ergon which means at work. energy at etymonline.com

Work and Energy
Work is also measured in joules, which shows their close relationship. Energy can be used to perform work; work can be made to increase the energy of a system. This is one way of stating an important principle, the work-energy theorem. The two quantities are not the same, any more than mass and energy are the same thing, but one can be converted into the other. Unlike the situation with mass and energy however, there is not 100% conversion. The system will always lose some energy as heat, which will increase the entropy, or disorder, of the system. Note that this does not mean that some of the energy somehow disappears. It is merely lost from the human point of view, but not in terms of the Universe. It is no longer in a form that is useful to us. Heat is a form of energy and "counts" in the conservation law, and entropy is a measure of the amount of disorder that is created by the dissipation of heat. See the second law of thermodynamics.

Conservation
Energy is a conserved quantity—so long as we are not considering nuclear changes. For many purposes it is sufficient to treat energy conservation as if it were a law of nature. This approach is taken in thermodynamics, chemistry, and most of high school physics (except in dealing with nuclear changes).

A more rigorous treatment of energy conservation requires that mass and energy be considered together: mass-energy is conserved using E=mc². This equation was discovered by Albert Einstein in 1905 as a corollary to his theory of special relativity.

Transfer and Transformation
Energy is particularly susceptible to measurement when being transferred (one object to another) or transformed (one type to another).

Examples of transfer include the flow of electricity from the outlet to your computer through the power cord and heat from a hot cup of coffee to your mouth. We have invented many devices that transform energy. For example, microphones change sound (a form of mechanical energy) into electromagnetic energy and loudspeakers change it back. Telephones have both. Nuclear power plants convert nuclear energy to thermal energy; the heat boils water into high pressure steam. The mechanical energy of the steam drives a generator that converts it to electromagnetic energy. You may use some of that energy at your house to recharge your laptop or camera battery, converting the electromagnetic energy to chemical energy. None of these processes is 100% efficient, so energy is converted into waste heat, more properly known as entropy, at every step along the way. When you use incandescent light bulbs, as much as 95% of the electrical energy is converted to heat (entropy) instead of light.

Quantization
To normal perception energy seems to flow in uneven amounts however at a subatomic level all energy moves in packets called quanta, or singular, quantum. Each quantum has the same amount of energy.

title: Energy


text:
Waves

Waves
Waves are the transfer of energy from one place to another in the form of a periodic disturbance. For example, when a stone is thrown onto a water surface, water molecules on the surface move up and down. As a water molecule moves it collides with the nearest water molecule and transfers energy to that molecule, thus setting it in motion.

Transverse and Longitudinal waves
There are two types of waves: Transverse and Longitudinal Waves.:
 * 1) Transverse Waves are waves that vibrate perpendicular to the direction of travel of the wave. Examples of Transverse Waves include, but are certainly not limited, to: Electro-Magnetic Waves*, Sine and Cosine Waves,and the wave of a string.
 * 2) Longitudinal Waves are waves that vibrate parallel to the direction of travel of the wave. They are also commonly referred to as Pressure or Compression Waves. Longitudinal waves include sound waves, (Although you wouldn't know it if you looked at sound waves on an osciliscope!) and the waves of a spring or slinky pulled back and forth

 * Electromagnetic Waves can travel through a vacuum. These waves are unique because they do not need a medium of travel unlike all other waves. Light and heat are examples of electromagnetic waves. Electromagnetic Waves travel at the speed of light and have no mass.

Equation for Velocity and Wavelength
In this equation: It can be understood as how frequently a certain distance is transversed.
 * f is the frequency (The number of peaks to pass a point in a given time, usually in Hz)
 * λ (The Greek letter lambda) is the wavelength (usually measured in meters)
 * V is the resulting velocity in m/s (meters per second). Wave speed is equal to the frequency times the wave length.

Medium
A medium is a substance through which a wave can travel. For example: Sound waves need a medium. It travels by the vibration of liquid,solid and gas.

Although some soundtrack wave can travel without a medium. For example: Visible light

Resources

 * Waves in plasmas

title: Waves


text:
Light and optics

Wikiversity resources

 * /Vision and lenses/
 * /Telescopes/

Sister links and other resources
[[File:Wikiversity and sisters logo.svg|240px|thumb|

Optics Geometrical optics Thin lens Paraxial approximation Accommodation (eye) Focus (optics) Optical aberration Corrective lens w:Category:Optics Physics Study Guide/Optics A few images from commons Lots of images from commons

]] A collapsable list of sister links is shown to the right. It is not yet complete -- feel free to add links to Wikipedia/Wikibooks.
 * See also this collection of images: /Gallery_and_resources/

Important external links on optics

 * Physics Classroom - Ray optics
 * Phet - Geometrical optics
 * Hyperphysics - Light and vision
 * Optics Express Optics open access journal

From Wikipedia
Geometrical optics, or ray optics, describes light propagation in terms of "rays". The "ray" in geometric optics is a concept that permits us to view light in an extremely primitive version of the "particle picture" of quantum mechanics (primitive because Einsteins "E=hf" is never needed or used). Rays bend (and may split in two) at any interface, may curve in a medium where the refractive index changes, and may be absorbed and reflected. This is a significant simplification of optics that fails to account for optical effects such as diffraction and interference. The approximation tends to be valid when the wavelength is very small compared with the size of structures with which the light interacts.

The image to the right shows how waves can form a ray if the wavelength is very small.

Reflection refers to the bouncing of light off an object in a fashion that resembles how a ball might bounce off a wall (neglecting any effects due to the fact that the ball is spinning). Glossy surfaces such as mirrors reflect light in a simple, predictable way: (1) The incident and reflected rays lie in a single plane, and (2) the angle between the reflected ray and the surface normal is the same as that between the incident ray and the normal.

 * Definition of "normal". The surface normal, a line perpendicular to the surface at the point where the ray hits.

This law applies to flat mirrors, as well as mirrors with curved surfaces (examples of curved surfaces include parabolic and spherical).

Refraction occurs when light travels through an area of space that has a changing index of refraction. The simplest case of refraction occurs when there is an interface between a uniform medium with index of refraction $$n_1$$ and another medium with index of refraction $$n_2$$. In such situations, Snell's Law describes the resulting deflection of the light ray:

 * $$n_1\sin\theta_1 = n_2\sin\theta_2\ $$

where $$\theta_1$$ and $$\theta_2$$ are the angles between the normal (to the interface) and the incident and refracted waves, respectively. As discussed in Wikipedia, the index of refraction is closely related to the speed of the wave in the material: n=c/v, where c is the speed of light in vacuum and v is the speed of light in the medium.

 * A device which produces converging or diverging light rays due to refraction is known as a lens. Thin lenses produce focal points on either side that can be modeled using the lensmaker's equation. In general, two types of lenses exist: convex lenses, which cause parallel light rays to converge, and concave lenses, which cause parallel light rays to diverge.

The paraxial approximation
The paraxial approximation can be used to derive simple equations involving lenses. A statement of the approximation involves the optical axis, which is a line that passes through the center of each lens and is oriented in a direction normal to the surface of the lens (at the center). The paraxial approximation is valid for rays that make a small angle to the optical axis of the system, and also lie close to the optical axis, throughout the system.

Further simplification occurs when we assume that the lenses are sufficiently thin; this is known as the thin lens approximation. In this approximation, two points, called focal points, are situated at equal lengths to the left and right of the lens. Focal points are denoted with the capital letter F, while the distance from the focal point to the center of a then lens is called the focal length, denoted by the lower case f.

Warning: The point where all the ray coming from a given point on an object is called the image, which is generally not the same as the focal point of a lens.

Viewing optics in two dimensions
It is instructive to use a ray optics kit to view lenses. A description of these images can be found on Wikipedia's Lens. Note how reality is a bit different from the simple model.

The three easy rays and the thin lens formula

The detailed prediction of how images are produced by these lenses can be made using either ray-tracing methods or equations. Thin lenses follow a simple equation that determines the location of the images given a particular focal length ($$f$$) and object distance ($$S_1$$):
 * $$\frac{1}{S_1} + \frac{1}{S_2} = \frac{1}{f} $$

where $$S_2$$ is the distance associated with the image and is considered by convention to be negative if on the same side of the lens as the object and positive if on the opposite side of the lens. The focal length f is considered negative for concave lenses.

Real image for converging lens occurs when S1 > f >0
It is customary with lenses to assume that the light travels from left to right, and in such cases, the convention is that the object distance S_1 is positive. If the lens is converging, f>0, and if S1>f, the equation above yields a value of S2 that is positive, which means that the image is to the right of the lens. Such an image is called a real image, because rays actually converge to that point.

Virtual image for converging lens occurs when 0 <S1 < f

If the object is moved closer to the lens than it's own focal length, the equations predict that S2 < 0. In this case the image is on the left of the lens. In other words, the rays on the right side of the lens are diverging as if they originated at a point to the left of the lens. Such an image is called a virtual image. When a magnifying glass is used in this way, it is impossible to converge all the light from a source to a single point. This situation does describe the use of a magnifying glass or reading glasses to better see something that is small and/or too close to the eye for comfortable viewing.

In this case it is worth noting that the rays continue to diverge after passing through the converging lens. But they diverge less. The question of whether a converging lens causes the rays to actually converge after passing through the lens is easy to answer:

 * 1) If the object distance is greater than the focal length of a converging lens (S1 > f > 0) the converging lens causes the rays to converge.
 * 2) If the object distance is less than the focal length converging lens (f > S1 0) the rays continue to diverge, but diverge less.
 * 3) If the object distance equals the focal length of a converging lens (S1 = f > 0) the rays neither converge nor diverge, but emerge parallel to each other.

Thoughts on infinity
If the rays are parallel, they are said to meet at infinity. If S1 = f, then our equation (1/S1 + 1/S2 = 1/f) yields what may seem like the meaningless result, S2 = 1/0. This is a good place to mention that "infinity" has a practical value. We can give meaning to this equation to the loosely defined mathematically statement,

 * $$\frac{1}{0} = \pm\infty $$ ,

$$\frac{1}{\pm 0} = \pm\infty $$ and $$\frac{1}{\pm \infty} = \pm 0$$

where $$\pm 0$$ is commonly used "shorthand" for an infinitesimally small number either slightly larger or smaller than zero. This idea is also sometimes represented as $$0^+$$ or $$0^-$$. It seems odd that zero-plus is almost equal to zero-minus, while plus and minus infinity seems far apart. See also point at infinity.

by noting that in practice one cannot put the image exactly at a given point, with 0% error. If "0" is a very small positive number, then 1/"0" is very large and positive. If "0" is very close to zero, but negative, then 1/"0" approaches negative infinity. It is customary to use superscripts to indicate the sign of a number that is approaching zero: 0- is negative and 0+ is positive. Physically, the two infinities (positive and negative) are also "nearly equal" in that both represent nearly parallel rays that either slightly diverge or slightly converge.

Virtual images from a diverging lens when f < 0
The formulas above may also be used for negative (diverging) lens by using a negative focal length (f), but for these lenses only virtual images can be formed.

More from Wikipedia
For students wishing to model the eye using the , the Lensmaker's equation states that

$$\dfrac{1}{f}=(n-1)\left(\dfrac{1}{R_2}-\dfrac{1}{R_2}\right)$$

There is also a more general version of the formula if the lens is placed inside a medium other than air:

$$\dfrac{1}{f}=\left(\dfrac{n_2}{n_1}-1\right)\left(\dfrac{1}{R_2}-\dfrac{1}{R_2}\right)$$

A number of consequences of these rules are discussed in Wikipedia's Geometrical optics

title: Light and optics


text:
Magnetism

Faraday's Law
The magnitude induced EMF through a loop of conducting material is equal to the magnitude of the time derivative rate of change of the magnetic flux through that loop.

 * $$\left|\frac{d\Phi_{B}}{dt}\right| = \left|e.m.f\right|$$

Lenz's Law
The polarity of the induced EMF is such that oppose the changes/current that causes it.

 * $$e.m.f = -N\frac{d\Phi_B}{dt}$$

Magnetic Field Strength
Magnetic Field Strength is defined as the force on one metre of wire carrying a current of one amp at right angles to the magnetic field. Magnetic Field Strength is also called flux density and is measured in teslas, T.

title: Magnetism


text:
The Atom

A Brief Introduction to The Atom
The word "atom" comes from the Greek "atomos" (named by Democritus) which means "indivisible" as it was thought in ancient times that atoms were the fundamental "units" of nature- they could not be split up into smaller constituents. However, now we know that atoms are not indivisible and that they are comprised of 3 sub-atomic particles known as protons, neutrons and electrons; where the protons and neutrons are comprised of even smaller fundamental particles called quarks and electrons are a type of fundamental particle in a group known as leptons- this is to do with particle physics, however, and so is not too relevant in this section.

Atoms are tiny constituents of matter (of molecules of compounds) which make up the entirety of the matter world we can see- all the stars, planets, nebulae etc. They consist of 3 main sub-atomic particles known as protons, neutrons and electrons; as mentioned earlier. Together, these 3 particles identify an element. The number of protons the nucleus of an atom contains gives its atomic number (z) on the periodic table- for example, the element Hydrogen has just one proton in its nucleus (giving z = 1) and 0 neutrons. The number of protons + the number of neutrons in an atom's nucleus gives the mass number (Ar) of the element/atom:

$$A_r = N_p + N_n = z + N_n$$

An atom with a neutral resultant ionic charge will have an equal number of protons and electrons, when C = 0:

$$z = N_e$$

The Atomic Structure
Atoms are comprised of mainly "empty space"- i.e. most of the space of an atom is a vaccuum. The protons and neutrons exist in the centre of the atom in the atomic nuclei- which is highly dense due to the compactness of the protons and neutrons- whereas the electrons exist in quantised energy levels surrounding the nucleus.

Note: It is a common misconception that electrons orbit the nucleus, there is uncertainty in their pattern of movement and so we say that they move in quantised energy levels surrounding the nucleus. If you're interested, we cannot know whether electrons orbit the nucleus due to Heisenberg's Uncertainty Principle which states that "we cannot know the exact position and momentum of a particle at any one time", or written mathematically:

$$\Delta x \Delta p \ge \frac{\hbar}{2}$$

Anyway, the size of an atom is often measured in nanometres (10-9 m) or even smaller. Even though they are so small, the whole atom is huge compared to the size of the nucleus situated at the centre of the atom, this analogy is a good one to use to put the size into context: If you were to expand an atom out to the size of Wembley Football Stadium, then the nucleus would be the size of a garden pea on the centre spot of the football pitch. This puts the structure of an atom into context and clearly shows that the nucleus of an atom is extremely dense seeing that, on average 99.9% of the mass of an atom is concentrated in the nucleus of the atom.

The Nucleus and Relative Masses
All the bound protons and neutrons in an atom make up a tiny atomic nucleus, and are collectively called nucleons. The radius of a nucleus is approximately equal to

$$1.07\sqrt[3]{A}$$

where A is the total number of nucleons, given by

$$\displaystyle\sum_{n=1}^k A_n = N_p + N_n$$

Atoms of the same element have the same number of protons, called the atomic number. Within a single element, the number of neutrons may vary, determining the isotope of that element. The total number of protons and neutrons determine the nuclide. The number of neutrons relative to the protons determines the stability of the nucleus, with certain isotopes undergoing radioactive decay.

The neutron and the proton are different types of fermions. The Pauli exclusion principle is a quantum mechanical effect that prohibits identical fermions, such as multiple protons, from occupying the same quantum physical state at the same time. Thus every proton in the nucleus must occupy a different state, with its own energy level, and the same rule applies to all of the neutrons. This prohibition does not apply to a proton and neutron occupying the same quantum state.

For atoms with low atomic numbers, a nucleus that has a different number of protons than neutrons can potentially drop to a lower energy state through a radioactive decay that causes the number of protons and neutrons to more closely match. As a result, atoms with roughly matching numbers of protons and neutrons are more stable against decay. However, with increasing atomic number, the mutual repulsion of the protons requires an increasing proportion of neutrons to maintain the stability of the nucleus, which modifies this trend.

The relative masses of the sub-atomic particles in an atom are as follows:

Proton = Ar = 1, Neutron = Ar = 1, Electron = Ar = $$\frac{1}{1870}$$

As the relative mass of an electron is so small, it is often ignored in calculations concerning the mass of an atom and the periodic table masses.

Relative Charges
The relative charges of the sub-atomic particles of an atom are also given here:

Proton = C = +1, Neutron = C = 0, Electron = C = -1.

As the neutron has a neutral charge it is ignored in ionic charge and oxidation/reduction calculations. As an aside, the protons and neutrons obtain their charges from the charges on the fundamental particles known as quarks- specifically of the flavours "up" and "down" quarks:

Up Quarks have an electric charge

$$C = +\frac{2}{3}$$

and Down Quarks have an electric charge

$$C = -\frac{1}{3}$$

from here it is easy to see what protons and neutrons are specifically comprised of. A proton is made up of 2 up quarks and 1 down quark:

$$C = \frac{2}{3} + \frac{2}{3} -\frac{1}{3} = \frac{3}{3} = 1$$

and neutrons are comprised of 1 up quark and 2 down quarks:

$$C = \frac{2}{3} - \frac{1}{3} - \frac{1}{3} = 0$$

where C obviously represents the relative charge.

title: The Atom


text:
Particle physics

At present, we understand that there are two categories of fundamental particles: bosons and fermions.

Fermions
Fermions are things that we normally associate with matter. Examples of fermions are quarks, which combine to make up protons and neutrons, and electrons. There are other more exotic particles that are fermions.

Quarks
Quarks are the basis of most elements in the present world, at the present day there are 6 known (non-anti-) quarks, these are:
 * Up
 * Down
 * Charm
 * Strange
 * Top
 * Bottom

Each of these have their own respective anti-quark; this adds up to a total of 12 quarks. For completeness, the antiquarks are listed here:

 * Antiup
 * Antidown
 * Anticharm
 * Antistrange
 * Antitop
 * Antibottom

Leptons
Leptons do not experience the strong interaction of the nuclear force. The leptons form a family of elementary particles that are distinct from the other known family of fermions: the quarks. There are 6 different Leptons in total, consisting of:
 * Electron
 * Muon
 * Tau Lepton
 * Electron Neutrino
 * Muon neutrino
 * Tau neutrino

The leptons have Anti-Leptons just like that of the Quarks although their names are different, the Anti-Leptons consist of;
 * Positron
 * Muon (no change)
 * Tau Lepton (no change)
 * Electron antineutrino
 * Muon antineutrino
 * Tau antineutrino

Bosons
Bosons are particles that mediate forces, such as light and gravity. Light is mediated by photons and gravity by gravitons. All Bosons have an integer spin, unlike Fermions. The Higgs Boson is a theoretical particle that has yet to be discovered. Scientists hope the Higgs Boson explain why some particles are heavy and others, like the photon, are massless.

Hadrons
Hadrons are strongly interacting composite subatomic particles. They are classified into two separate classes, which are: Both of these consist of quarks.
 * Baryons
 * Mesons

Baryons
Baryons are strongly interacting Fermions, such as a Proton or a Neutron, both of which are made up 3 Quarks. Baryons have a baryon number of 1. The list of Baryons consist of:
 * Proton
 * Neutron
 * Delta
 * Lambda
 * Sigma
 * Xi
 * Omega

Mesons
Mesons are strongly interacting Bosons which consist of a quark and an antiquark. Mesons have baryon number 0. They are classified according to their quark content and their angular momenta.

Neutral mesons can spontaneously change their quark content in a process known as mixing. This process was first discovered in the neutral kaon system in 1964 and has since been observed in the neutral $$B$$ system, the $$B_s$$ system and the neutral $$D$$ system.

The ground state mesons are:

Mesons consisting of a quark and an antiquark of the same flavor do not have a unambiguous quark content. For example, the neutral pion is a superposition of flavor state $$u\bar{u}$$ and $$d\bar{d}$$. Other neutral states of this kind are shown below:

The top quark decays too rapidly to form bound mesonic states.

title: Particle physics


text:
User:Derian

Hi. I am derian. Too lazy to edit this page right now, probably a little bit later ))

title: User:Derian


text:
User:Wolfgrab

Applications Engineer B & R Automation USA www.br-automation.com

title: User:Wolfgrab


text:
User talk:Wolfgrab

School:Engineering
Welcome Wolfgrab! Would you be interested in helping out in the engineering school? --Rayc 00:32, 1 September 2006 (UTC)

title: User talk:Wolfgrab


text:
User talk:Uezeilo~enwikiversity

Your account will be renamed
Hello,

The developer team at Wikimedia is making some changes to how accounts work, as part of our on-going efforts to provide new and better tools for our users like cross-wiki notifications. These changes will mean you have the same account name everywhere. This will let us give you new features that will help you edit and discuss better, and allow more flexible user permissions for tools. One of the side-effects of this is that user accounts will now have to be unique across all 900 Wikimedia wikis. See the announcement for more information.

Unfortunately, your account clashes with another account also called Uezeilo. To make sure that both of you can use all Wikimedia projects in future, we have reserved the name Uezeilo~enwikiversity that only you will have. If you like it, you don't have to do anything. If you do not like it, you can pick out a different name.

Your account will still work as before, and you will be credited for all your edits made so far, but you will have to use the new account name when you log in.

Sorry for the inconvenience.

Yours, Keegan Peterzell Community Liaison, Wikimedia Foundation 00:09, 18 March 2015 (UTC)

Renamed
 This account has been renamed as part of single-user login finalisation. If you own this account you can |log in using your previous username and password for more information. If you do not like this account's new name, you can choose your own using this form after logging in: . -- Keegan (WMF) (talk) 06:24, 19 April 2015 (UTC)

title: User talk:Uezeilo~enwikiversity


text: User talk:Nyatsanga

title: User talk:Nyatsanga


text: User talk:Etchgirllearning

title: User talk:Etchgirllearning


text:
User talk:Mistalizad~enwikiversity

Your account will be renamed
Hello,

The developer team at Wikimedia is making some changes to how accounts work, as part of our on-going efforts to provide new and better tools for our users like cross-wiki notifications. These changes will mean you have the same account name everywhere. This will let us give you new features that will help you edit and discuss better, and allow more flexible user permissions for tools. One of the side-effects of this is that user accounts will now have to be unique across all 900 Wikimedia wikis. See the announcement for more information.

Unfortunately, your account clashes with another account also called Mistalizad. To make sure that both of you can use all Wikimedia projects in future, we have reserved the name Mistalizad~enwikiversity that only you will have. If you like it, you don't have to do anything. If you do not like it, you can pick out a different name.

Your account will still work as before, and you will be credited for all your edits made so far, but you will have to use the new account name when you log in.

Sorry for the inconvenience.

Yours, Keegan Peterzell Community Liaison, Wikimedia Foundation 23:38, 17 March 2015 (UTC)

Renamed
 This account has been renamed as part of single-user login finalisation. If you own this account you can |log in using your previous username and password for more information. If you do not like this account's new name, you can choose your own using this form after logging in: . -- Keegan (WMF) (talk) 06:16, 19 April 2015 (UTC)

title: User talk:Mistalizad~enwikiversity


text: User talk:Derian

title: User talk:Derian


text: Template:Policy planning

title: Template:Policy planning


text:
User talk:Duffman~enwikiversity

Your account will be renamed
Hello,

The developer team at Wikimedia is making some changes to how accounts work, as part of our on-going efforts to provide new and better tools for our users like cross-wiki notifications. These changes will mean you have the same account name everywhere. This will let us give you new features that will help you edit and discuss better, and allow more flexible user permissions for tools. One of the side-effects of this is that user accounts will now have to be unique across all 900 Wikimedia wikis. See the announcement for more information.

Unfortunately, your account clashes with another account also called Duffman. To make sure that both of you can use all Wikimedia projects in future, we have reserved the name Duffman~enwikiversity that only you will have. If you like it, you don't have to do anything. If you do not like it, you can pick out a different name.

Your account will still work as before, and you will be credited for all your edits made so far, but you will have to use the new account name when you log in.

Sorry for the inconvenience.

Yours, Keegan Peterzell Community Liaison, Wikimedia Foundation 23:31, 17 March 2015 (UTC)

Renamed
 This account has been renamed as part of single-user login finalisation. If you own this account you can |log in using your previous username and password for more information. If you do not like this account's new name, you can choose your own using this form after logging in: . -- Keegan (WMF) (talk) 06:06, 19 April 2015 (UTC)

title: User talk:Duffman~enwikiversity


text:
User:Pianist~enwikiversity

Intrests:

 * 1) Music - Piano + Composition
 * 2) History - France ~ 18th Century + Russia 20th Century

title: User:Pianist~enwikiversity


text:
User:Magus~enwikiversity

I am currently inactive.

title: User:Magus~enwikiversity


text:
User:Fabartus

W:User:Fabartus

title: User:Fabartus


text:
Category:Research policy proposals

Discussions related to the development of research poilicy are going to be conducted in a multi-lingual format at beta.wikiversity.org.

title: Category:Research policy proposals


text:
User talk:Preadaptation

Welcome to Wikiversity. I like your username. --JWSchmidt 20:07, 29 August 2006 (UTC)

Hello and thanks! This is quite interesting.. It looks to be quite a learning experience. I hope my contributions are of a positive nature.

Is this how one adds comments?

 * You might want to try this introduction if you are new to wikis. It is an introduction to our sister project, Wikipedia, but it shows how to use the wiki interface (Wikiversity is so new that nobody has yet made a good introductory tutorialhere). Also, try the "help" link on the left hand sidebar. --JWSchmidt 20:33, 29 August 2006 (UTC)

title: User talk:Preadaptation


text:
User:Duffman~enwikiversity

Duffman is mostly active on the Norwegian Wikipedia.

 * /Sandbox
 * /monobook.css
 * Special:Prefixindex/User:Duffman

title: User:Duffman~enwikiversity


text:
Work and energy

The work done by any force from one location to another is mathematically defined to be:

$$W = \int\limits_{\overrightarrow{\mathbf{l_0}}}^{\overrightarrow{\mathbf{l}}}\overrightarrow{\mathbf{F}} \cdot \operatorname{d}\!\overrightarrow{\mathbf{l}} $$

where F is the component of force parallel to the object's path at that given instant and L is the object's displacement. It follows that a force perpendicular to the path of the object does not do any work, such as the Sun's gravity's pull on Earth. This integral is a line integral along the object's path, and represents the sum of all the dot products of each infinitesimal displacement and the force at that location.

For a constant force acting in one direction, this equation reduces to

$$W = F\Delta l$$

A conservative force is one where the work done by it only depends on the starting and ending positions, while a non-conservative force, which comprises the vast majority of everyday forces, does not necessarily do the same work for the same overall displacement.

Energy
See the main article, Energy

In this topic we'll use only mechanical energies. There are two kinds of mechanical energies, potential and kinetic. These energies can transform to one to another like all other kinds of energies, but their sum, the total mechanical energy, is constant.

Work-energy principle
The work-energy principle states that the work done on an object is equal to the change in its kinetic energy:

$$W = \Delta K$$

Potential energy
The potential energy of an object with respect to a conservative force is the work that conservative force could potentially do to it, which would be a change of energy, in accordance with the work-energy principle. Potential energy is a relative concept; we are only concerned with changes in potential energy and not the absolute value of it.

A common example is gravity. The work gravity could potentially do is

$$U = -W = -\int\limits_{\overrightarrow{\mathbf{l}}}^{\overrightarrow{\mathbf{l_0}}}\overrightarrow{\mathbf{F}} \cdot \operatorname{d}\!\overrightarrow{\mathbf{l}} = \int\limits_{h_0}^{h} g \operatorname{d}h = mgh - mgh_0$$

It does not matter what h0 is, as long as gravity can be considered to be a constant, conservative force, and the difference in h is the same.

In multiple dimensions, it follows from the gradient theorem that $$\mathbf{F}=-\nabla U$$ where $$\nabla U = \frac{\partial U}{\partial x}+\frac{\partial U}{\partial y}+\frac{\partial U}{\partial z}$$.

Kinetic energy
The kinetic energy of an object is the total work that has been done to the object to place it in motion. By the work-energy principle, and Newton's second law:

$$K = \int\limits_{l_0}^l \mathbf{F}\cdot d\mathbf{L} = \int\limits_{l_0}^l \frac{d\mathbf{p}}{dt} \cdot d\mathbf{L} = \int\limits_{l_0}^l d\mathbf{p} \cdot \frac{d\mathbf{L}}{dt} = \int\limits_{l_0}^l \mathbf{v} \cdot d\mathbf{p}$$

In classical mechanics, $$\overrightarrow{\mathbf{p}} = m\overrightarrow{\mathbf{v}}$$ and $$d\mathbf{p}=md\mathbf{v}$$, so we have: $$\int\limits_{l_0}^l \mathbf{v} \cdot d\mathbf{p} = \int\limits_{v_0}^v m\mathbf{v}\cdot d\mathbf{v} $$, and because $$\mathbf{v}\cdot d\mathbf{v}=\frac{1}{2}d(\mathbf{v}\cdot\mathbf{v})=\frac{1}{2}d(v^2)=v dv$$: $$W=\int\limits_{v_0}^v mv\times dv = \frac{1}{2}mv^2 - \frac{1}{2}mv_0^2$$

For the total kinetic energy l0=0, and v0=0, so classically,

$$K=\frac{1}{2}mv^2$$

Total mechanical energy
The total mechanical energy of a system, in the absence of external forces, will always be constant. It is the sum of an object's kinetic and potential energies:

$$E=U+K$$

title: Work and energy


text:
Conservation of energy

Conservation of energy (the First Law of Thermodynamics) is a simple law stating that although energy may change form, it cannot disappear altogether, nor can it be created.

More recently, this law has been modified to take into account the equivalence of mass and energy ($$E = mc^2$$) discovered by Einstein. This new law is called the law of conservation of mass and energy. It states that although mass may convert to energy, and vice versa, neither may disappear without compensation in the other quantity. However, the original form of the law is adequate in most everyday situations.

A concrete example of energy conservation is found with falling objects. Near the surface of the Earth, the gravitational potential energy of an object is given by $$mgh$$, where m is the object's mass, g is the acceleration due to gravity at that place, and h is the object's height from where the object started to where it is now (measure with downward values negative). When an object falls, its potential energy is converted into kinetic energy (given by $$(1/2)mv^2$$). In math:

$$-mgh = \frac{1}{2}mv^2 $$

where m is mass, v is velocity. There is a negative sign in front of the potential energy because when the object is gaining kinetic energy, it will be losing potential energy.

Another, more useful way of interpreting conservation of energy is by using the following formula

$$K_1+U_1+W other=K_2+U_2$$

title: Conservation of energy


text:
Visual Basic/Variables and Types

This lesson will instruct you on the creation of variables in Visual Basic 6, as well as variable types. This lesson requires a very basic understanding of the interface in Visual Basic 6. If you have not done so already, it is recommended that you read the Introduction to VB6.

Setting Up The Project
The code that you type between these two lines will be executed when your program launches. Because of that, its a handy place to try out the new concepts like the ones you'll be learning in this article.
 * 1) Create a Standard EXE in the same way that you did in the previous lesson.
 * 2) Double-click anywhere in the blank content of your form. This will bring up the code editor with the following code:

Object Types and Naming Scheme
These are very important things to remember in order to make your source code more easily intelligible.

File Types
You will use various file types while using VB6. These are some the most common ones.
 * File type: What people call it
 * Prefix: What people prefix the filename with
 * Extension: What file extension is used
 * Description: What its used for most often

Examples of common file names:
 * OddCalc.vbp
 * frmMain.frm
 * frmAbout.frm
 * frmPrintInvoice.frm
 * modMain.bas
 * modSettings.bas
 * modDeclares.bas
 * modWinsock.bas
 * clsWinsock.cls
 * ucCustomButton.ctl
 * ucTreeView.ctl
 * ucWinsock.ctl

Variables
A variable is a word or letter used to reference data used in a program. That data may be an integer like "23", a floating point number like "23.23", a string like "Hello World!", and many other data type.

Variable Names
The following are the requirements when naming the variables in Visual Basic:
 * It must be less than 255 characters
 * No spacing is allowed
 * It must not begin with a number
 * Period (dot) is not permitted

For the sake of making sure other people can look at your code and know what you were thinking:
 * Prefix your variable name with the appropriate prefix for your variable's data type.
 * Make sure the body of your variable name makes it easy to tell what its used for.
 * Don't use an ambiguous name like "intUhhhh" or "strX" unless its use is within a very small scope of the program, and even then try not to do it much. Try using descriptive names. For example, to save the total marks sustained by a particular person in an integer, use something like int Marks/Marks Sustained rather than a random string of characters.

Using variables
In order to use a variable it must first be declared, then its usually modified to represent some sort of value, then its often outputted in some way so that you can see a result from it.

Example variable declaration, Setting, and Output: Example variable declaration, Setting, Modification, and Output: Now, go put those lines between Private Sub Form_Load and End Sub in your program to execute those instructions when the program starts.

Variable Declaration Scope
The keyword used to declare a variable and the location in which its declared defines the scope and duration in which a variable is available.

Keyword: Declaration location: Scope: Duration:
 * The first word used in a variable declaration
 * "Procedure" means the variable is declared within a Sub, Function, or Property
 * "Module" means the variable is declared near the top of the module, not inside a procedure
 * "Procedure" means the variable is available only within the Sub, Function, or Property in which it was defined
 * "Module" means the variable is available only within the module in which it was defined
 * "Project" means the variable is available throughout all modules in the project
 * "Procedure" means the variable's value is gone once the procedure its available in has finished
 * "Application" means the variable's value will remain throughout running of the program

Data Types
Data Types are classifications of what sort of data is contained inside of a variable. Variables of certain data types may only contain values which are acceptable for that data type. The following tables describe the data types available in VB6. You may select any of the words under the column "Type" in order to use that data type.

Examples:

Control Types
Examples of common object names:
 * txtName
 * txtAddress
 * cboYear
 * cmdOK
 * cmdCancel

Visual Basic/Les types en VB

title: Visual Basic/Variables and Types


text:
User:Neo139

http://en.wikipedia.org/wiki/User:Neo139
 * My profile is in English Wikipedia.
 * Mijn profiel is in Engelse Wikipedia
 * Mon profil est dans Wikipedia anglais
 * Mein Profil ist in englischem Wikipedia
 * Το σχεδιάγραμμά μου είναι σε αγγλικό Wikipedia
 * Il mio profilo è in Wikipedia inglese
 * Meu perfil está em Wikipedia inglês
 * Мой профиль находится на английском языке Wikipedia
 * Mi prerfil esta en Wikipedia en Ingles

title: User:Neo139