The term "power" has many different meanings in the English language. In physics, however, power has a very specific meaning. It is the rate of transfer of energy; the measurement of the amount of energy transferred in a unit amount of time.

In physics there is a fundamental principle that says energy can never be used up or destroyed. Energy converts from one form of energy to another. In a car, the chemical energy locked in gasoline is converted to heat energy in the explosion within the cylinders. This energy is converted to kinetic energy in the pistons and wheels of the car. All this energy is finally converted again to low grade heat energy through the friction of the moving parts, tires on the road and the air rushing past the body of the car. What actually takes place is conservation of energy as it changes form...