ENERGY

Energy is the capacity of a body to perform transformations and do work.

1.Forms of energy:

2.Units of measurement for energy:

In the International System, energy is measured in joules. When energy takes the form of heat, we often express in calories.


3.Power
The power of a machine is the amount of work that it can do in a certain amount of time. We express this relationship as:       P=W/t
The relationship between input and output energy in any machine is expressed as its energy conversion efficiency:           Energy conversion efficiency(%)=(output/input)·100