# Law of conservation of energy

Don’t confuse the words conversion and conservation.

Energy cannot be created or destroyed. You may need to describe how energy is transferred in different situations, but remember that total energy is always conserved: the total energy at the start and at the end must have the same total value.

So you must account for all of the energy, and that includes the internal energy that will have been created, as well perhaps as light or sound. for example, the tram takes electrical energy and converts it mainly into kinetic energy, but also into internal energy and sound.

You can use the principle of the conservation of energy to calculate what happens when kinetic energy and potential energy are converted from either one to the other.

So long as negligible energy is lost in the conversion,

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