Capacity or ability to do work is called energy.
To do any work, energy is used. A body is said to poses energy when it is capable of doing work or of overcoming resistance. Thus work and energy have a strong relationship. Energy is spent, when work i s done. Energy is the stored capacity to do work.
Our three main sources of energy are the sun, atom and the earth’s hot interior.
In simple term, power is the rate of ding work. The rate at which the work is being done is expressed by the amount of work done. In other words, it also means the rate at which energy is being consumed. If the rate of energy consumption is fast, so the power will also be higher.
The unit usually employed to measure power is watt. In machines power is measured in `Horse power’. One Horse power is equivalent to 745.700 Watts or 33,000 pounds lifted one foot in one minute. In short, Horse power is known as Horse power. This unit was devised by the great engineer James watt and it was estimate of the rate at which a good horse could work for a few hours, though he deliberately fixed it at a high amount.
It may be added here that the domestic electricity consumption is measured in terms of Kilowatt-hour (kwh). Kilo –watt hour is the work performed by one kilowatt of electric power in one hour. Price of electrical energy is based on this unit.