Energy

The fact that people can hear is a simple demonstration of the fact that sound is a form of energy. Sound is actually nothing other than the movement of air. When sound is created, sound waves travel through space, creating compressions in some regions and rarefactions in other regions. When these sound waves strike the human eardrum, they cause the drum to vibrate, creating the sensation of sound in the brain. Similar kinds of sound waves are responsible for the destruction caused by explosions. The sound waves collide with building, trees, people, and other objects, causing damage to them.

Chemical energy is a form of energy that results from the forces of attraction that hold atoms and other particles together in molecules. In water, for example, hydrogen atoms are joined to oxygen atoms by means of strong forces known as chemical bonds. If those are broken, the forces are released in the form of chemical energy. When a substance is burned, chemical energy is released. Burning (combustion or oxidation) is the process by which chemical bonds in a fuel and in oxygen molecules are broken and new chemical bonds are formed. The total energy in the new chemical bonds is less than it was in the original chemical bonds, and the difference is released in the form of chemical energy.

Nuclear energy is similar to chemical energy except that the bonds involved are those that hold together the particles of a nucleus, protons and neutrons. The fact that most atomic nuclei are stable is proof that some very strong nuclear forces exist. Protons are positively charged and one would expect that they would repel each other, blowing apart a nucleus. Since that does not happen, some kinds of force must exist to hold the nucleus together.

One such force is known as the strong force. If something happens to cause a nucleus to break apart, the strong force holding two protons together is released in the form of nuclear energy. That is what happens in an atomic (fission) bomb. A uranium nucleus breaks apart into two roughly equal pieces, and some of the strong force holding protons together is released as nuclear energy.