Energy is the name given to the ability to do work. There are various forms of energy such as Mechanical Energy, Chemical Energy, Electrical Energy, Atomic Energy or Solar Energy. Energy of various kinds is often made available by chemical changes. It can also be produced from physical changes. The following are examples of how energy is used. The jet aircraft gets its power from jet turbines. These powerful jet engines create a high-pressure stream of very hot gases that push the aircraft forward as they leave the engine. This is an example of heat being transformed into movement or Mechanical Energy. However, this transformation could not take place without the fuel that the aircraft gets within its wings or fuselage. Fuel is considered a chemical energy. Fuel can take the form of gases, solids or liquids. When fuels combine with oxygen from the air, they release their stored energy as heat. This process is called burning. The individual relies on food for fuel which contains energy-giving substances that our bodies can store until we need this energy to use our muscles. When we do use our muscles within us, we may not always be sure that heat is given off. Our bodies do not burst into flames but the perspiration on our skin is a clue to what is happening. The movement of the windsurfer has a different explanation. The windsurfer is propelled along by a sail which collects mechanical energy from the winds that sweep along the water. This energy has been produced by the sun which warms the earth's surface and sets the air above in motion. The sun's heat comes to the earth as a form of radiant energy. When the heat reaches the surface of the earth, it causes the land or seas to rise in temperature. The sun is very hot. In fact, the center of the sun can reach temperatures of up to 27 million degrees Fahrenheit. This is because of another kind of energy reaction where new substances are continually being created as others are being destroyed. This reaction is known to us as the Nuclear Reaction. Today we are trying to imitate this reaction in improving our energy supply. Scientists have calculated that the sun has enough fuel to go on producing energy at its present rate for about five billion years. On earth man-made nuclear reactions are used to produce a form of power we know as electricity. Electricity can be transformed into other kinds of energy such as heat, light and radio waves. Humans have also used the idea of nuclear reactions as a type of weapon. We call this powerful weapon the Atomic Bomb. Electrical energy can also be used to produce laser beams. This involves energy being concentrated to a specific narrow point where the impact of so much power creates heat able to cut through metals. Bibliography: Frazer, Frank Trewin. Discovering Energy. Copplestone Books Ltd, 1981. "Energy" Encyclopedia Britannica, Vol. 6 Encyclopedia Britannica, 1979.