A small force moving an object a long way can produce the same amount of work as a large force over a small distance. Energy Energy is defined as the ability to do work. If a system can exert a force over some sort of distance then the system possesses energy. The amount of a system s energy is a measure of how much work the system could do. When a system runs out of energy then it can no longer do any work.
More power is needed to run up a flight of stairs than to walk up.
Note that the work is equivalent, you moved your mass a distance, but the time was different. The watt is a unit of power, and 1000 watts is called a kilowatt . The rating of 100 watts on a light bulb is telling us the rate at which energy is being consumed when the light bulb is on. When you pay your energy bills, for instance electricity, you pay based upon how much energy you consume. This means that a 100 watt light bulb cost 1 cent an hour to operate.