Conversion of common energy units. Use the calculator below to convert between MWh (Megawatt-hour), KWh (Kilowatt-hour), W (watt-hour) and BTU like: KWh to Btu, Btu to KWh, MWh to KWh and so on.
Concept of Energy
To understand the concept of energy you should firstly understand the concept of work. Suppose you push a table across your dinning room floor. Then the measure of the work done is equal to the force you pushed with, multiplied by the distance over which you did the pushing. It can be expressed by the formula:Work = Force x Distance
Knowing this you can understand the scientific definition of energy:
The energy of an object, or of a system, is the work that the object or system can do on some other object or system.
In other words, energy measures the capability of an object or system to do work on another system or object. For example, someone pushing (exerting a force on) a table across a room floor has the capability to do work because his/her body has a certain amount of chemical energy from the food that person eat.
Energy has a number of different types, all of which measure the ability of an object or system to do work on another object or system. Some forms of energy: chemical energy, electrical energy, heat (thermal energy), light (radiant energy), mechanical energy, and nuclear energy.
There are two basic forms of energy:
- Stored energy is called potential energy.
- Moving energy (energy which is in moving objects) is called kinetic energy.
Common Units of Energy
- The Joule Joule, unit of energy in the International System of Units (SI); One Joule is equal to the work done by a force of one newton acting through one meter. One joule equals approximately 0.7377 foot-pounds. One Joule equals one watt-second in electrical terms.
- The kilowatt-hour is a unit of energy used by electrical utilities. The kilowatt-hour is a unit of energy equivalent to one thousand watts of energy expended for one hour (1 h) of time. One kilowatt-hour (kWh) = 3.6 x 106 J = 3.6 million Joules
- One calorie of heat is the amount needed to raise 1 gram of water 1 degree Centigrade. It is equal to 4.184 J (Joules). Note that calories in food ratings are actually kilocalories.
- A British thermal unit (Btu) is a measure of the quantity of heat, defined as approximately equal to 1,055 joules, or 252 gram-calories. It was formerly defined as the amount of heat required to raise the temperature of one pound of water 1° F.