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Chemistry and physics lessons
atom physics lesson

Mechanics

Free online mechanics lesson for elementary school,  middle school and high school.
chemistry high school
 

Science class

Chemistry

Electricity

Optics

Mechanics
Mechanics lessons
Gravity
- The solar system - motions of celestial bodies
- Physical interactions
- Effects of gravity
- Weight of an object
- Difference between weight and mass
- Relationship between weight and mass 

Energy
- Energy basics
- Potential energy
- Kinetic energy
- Mechanical energy
- Translational Kinetic Energy
- kinetic energy mass and speed









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Gravity

Energy basics

 
1) What is energy ?

The concept of energy is linked to various situations but it can be defined as follows:
An object owns energy if it can acts on itself or on another object.

In this definition " to act " means there can be modifications of:
- shape
- trajectory
- speed
- position
- température
- pressure
- chemical composition
- electrical state
- magnetical state
etc

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2) Main types of energy

main forms of energy are:
- Kynetic energy (motion energy)
- Potential energy ( position energy )
- Chemical energy 
The light energy 
- Electrical energy
- heat energy


3) Transfers and energy conversions

When an object gives a part of its energy to another object there is an energy transfer.
When energy changes its form, there is an energy conversion.
Lorsque l'énergie d'un corps est transmise à d'autres corps on parle alors de transfert d'énergie.

Lorsque l'énergie d'un corps change de forme on parle alors de conversion d'énergie.

Talking about chemical transformations, the french chemist Lavoisier established a simple rule:
" Nothing is lost, nothing is created, everything is transformed "
This rule also applies for energy:
- If an object's energy decreases it isn't lost: this energy is transfered to another object or converted in another type of energy.
- If an object's energy increases it is not created from nothing: this energy comes from another object, or results from an energy conversion.
To sum up, every energy change can be explained by a transfer or a conversion.


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