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



Mechanical energy

1) What is mechanical energy ?

The conversion of potential energy into kinetic energy for a falling object indicates a link between these two forms of energy. This link has led to define a new kind of energy: mechanical energy.
Several symbols can be used: sometimes ME, TME or U
Like other kinds of energy, mechanical energy can be expressed in joule.

Definition: mechanical energy is the sum of kinetic energy and potential energy
Mechanical energy = kinetic energy + potential energy
ME = KE + PE

2) Conservation of mechanical energy

If an object does not exchange energy with another object, its mechanical energy remains constant.
If mechanical energy does not vary, it implies that every change of kinetic energy is simultaneously accompained by the opposite change of potential energy ( and reciprocally ).

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