There are many different forms of potential energy all around us. The book on your desk and the food you ate for breakfast represent just a few forms of potential energy. All forms of potential energy have the stored ability to move matter.

Gravitational
Gravity is a force of attraction that exists between any two objects. Gravitational potential energy is stored energy that depends on three things: the mass of an object, the height or potential falling distance of that object, and the acceleration of the object due to gravity.

An apple hanging on a tree has gravitational potential energy because it is being pulled toward a very large object — Earth. It has the potential to fall a distance. The higher up on the tree and the greater its mass, the more gravitational potential energy it has.

In the 17th century, Sir Isaac Newton described gravity as a force of attraction and devised equations to explain its behavior. Over 200 years later, Albert Einstein theorized that gravity warped space and produced distorted paths along which objects moved as illustrated at right. Today gravity remains a mystery. An alternate theory proposes the existence of tiny, gravity-producing particles called gravitons. Perhaps in the future, you will be the scientist who will solve the mystery of gravity.

	Elastic potential energy is also found in another common action — bouncing a ball. When a round ball strikes a hard surface, the round ball flattens where it hits the surface. Even though the change may be too slight and quick to observe, striking the surface alters the tension in the ball’s material. Like a stretched rubber band snapping back to form, the ball returns to its round appearance. As it reshapes, it pushes off the hard surface, resulting in a bounce.

Elastic
Stretch a rubber band. Now release it. What happens? The rubber band snaps back to its original length. The energy that powered this rapid return to the shorter, original length is another form of stored energy called elastic potential energy. As you stretched the band, you changed its shape. When the ends of the band were released, this stored energy was transformed into the "snap," or movement back into the original, more stable shape.

Magnetic
Bring two magnets together. Depending on which ends face each other, the magnets will either pull together or push apart. This attraction or repulsion is a result of the magnetic potential energy stored in these objects. This same magnetic potential energy is found in the coronal mass ejections (CMEs) studied by Dr. Janet Green. CMEs carry with them a part of the sun's magnetic field, impacting our planet in many ways.

Electrostatic
Another form of potential energy, electrostatic potential energy, arises from the attraction and repulsion of electrical charges and occurs when certain materials are brought together. If you have ever had a clean sock stick to your clothes after it was removed from the dryer, you have experienced the effects of electrostatic potential energy.

Chemical potential energy exists within the chemical bonds of substances, such as gasoline. Ignited by a spark in the car's engine, gasoline molecules react with oxygen, producing an explosive reaction. During this process, chemical energy that had been stored in the bonds of the fuel molecules is released. Through a series of energy transfers and transformations, the vehicle moves. The Conservation of Mass is maintained because the mass of the gasoline and oxygen that react equals the mass of carbon dioxide and other emissions produced.

Chemical Chemical potential energy is energy stored within the bonds of a substance. Although you cannot see the stored energy, you can experience its effect when substances react. In any chemical reaction, Conservation of Mass is maintained. Although bonds are broken and new substances are formed, the total amount of matter does not change. Nuclear Nuclear potential energy is the energy stored in the bonds of subatomic particles. The atom's nucleus contains most of this energy. This energy can be released by either splitting or fusing atoms through the processes of fission and fusion. In these reactions, some mass is transformed into energy.