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.
definition " to act " means there can be modifications of:
Main types of energy
of energy are:
energy (motion energy)
energy ( position energy )
- heat energy
Transfers and energy conversions
object gives a part of its energy to another object there is an energy
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.
l'énergie d'un corps change de forme on parle alors
de conversion d'énergie.
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.