UNITS OF MEASUREMENT FOR ENERGY AND POWER

In the International System, energy is measured in joules.
When energy takes the form of heat, we often express it as calories.
The relationship between calories and joules is: 1 cal = 4.18 J.
 POWER.
Power is a measurement of how quickly work is done.
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
P: POWER.
W: AMOUNT OF WORK.
T: TIME.
The relationship between input and output energy in any machine is expressed as its energy conversion efficiency:
Energy conversion efficiency (%) = output/input x 100