# Principle of Conservation of Energy | Definition, Examples – Work, Energy and Power

Conservation of Energy Physics:
Conservation of energy can be rigorously proven by Noether’s theorem as a consequence of continuous time translation symmetry; that is, from the fact that the laws of physics do not change over time.

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## Principle of Conservation of Energy | Definition, Examples – Work, Energy and Power

Principle of Conservation of Energy:
Energy can neither be created nor be destroyed, it can only be transferred from one form to another form.

In physics, the term conservation refers to something which doesn’t change. This means that the variable in an equation which represents a conserved quantity is constant over time. It has the same value both before and after an event.

Principle of Conservation of Mechanical Energy:
For conservative forces, the total mechanical energy (sum of kinetic and potential energies) of any object remains constant.

Many devices are used to convert mechanical energy to or from other forms of energy, e.g. an electric motor converts electrical energy to mechanical energy, an electric generator converts mechanical energy into electrical energy and a heat engine converts heat energy to mechanical energy.

Mechanical Energy Examples:

• Hammer
• Dart Gun
• Wind Mill
• Bowling Ball

Work, Energy and Power:
Work, energy and power are the three quantities which are inter-related to each other. The rate of doing work is called power. An equal amount of energy is consumed to do a work. So, basically the power is the rate at which energy is consumed to complete a work.