one example of conversation of mechanical energy to electrical energy is
Mechanical energy 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 steam engine converts heat energy to mechanical energy.
First law of thermodynamics It states that the change in the internal energy Î”U of a closed system is equal to the amount of heat Q supplied to the system, minus the amount of work W done by the system on its surroundings. An equivalent statement is that perpetual motion machines of the first kind are impossible.