Difference Between Work And Energy
Energy is the ability to do work. However, to understand energy we must understand what scientists mean by “work.” It might seem that it is work to try to solve a problem or to stand at attention for 15 minutes. But that is not “work” to a scientist.
In science, work is motion against resistance. Lifting a box against the pull of gravity is work, as is driving a nail into a board against the friction of the wood or winding a clock against the resistance of the spring.
In doing this work (or any other kind), energy is used up. Both work and energy are measured according to the distance an object is moved and the force that must be overcome to keep the object moving. Suppose a pound of iron is lifted 1 foot. Then 1 foot-pound of work has been performed and 1 foot-pound of energy has been used up.
Work can be done in various ways. Each way represents a different kind of energy. For instance, you can drive a spike into the ground against the resistance of hard soil by dropping a weight on it. It is the motion of the weight that does the work. (If you placed the weight very gently on the spike, nothing would happen.) The moving weight is said to have kinetic energy. (“Kinetic” comes from a Greek word meaning “motion.”)
Suppose you hold the weight high above the spike. As soon as you let go, it starts falling and becomes capable of doing work. While you are actually holding it, however, the ability to do work is only potential. That is, the ability can exist in the future but does not in the present. A weight held high in the air possesses potential energy.
In the same way, a rubber band that is stretched and held has potential energy. If the hold is released, the rubber band contracts. It possesses kinetic energy while it is contracting. Kinetic energy and potential energy can be lumped together as mechanical energy.
Imagine now that you have a corked glass flask with a little water at the bottom. On heating the flask, the water boils and begins to turn into steam. The steam pressure builds up as a kind of potential energy and then turns into kinetic energy when the cork flies out with a loud pop. The cork was moved against the friction of the neck of the flask (which was holding the cork in place). This motion against a force is work. The motion was caused by the heat that formed the steam. This is known as heat energy.
A magnet can lift a nail against gravity. Sometimes an electric current is passed through wires wound around an ordinary iron bar. This changes the bar into an electromagnet that will lift a nail against gravity. When electricity and magnetism do work in this way, they are known as electric energy and magnetic energy.
In any chemical compound there are attractions that hold atoms in place, against their own natural tendency to move about. This is a kind of potential energy, like that of a stretched rubber band. (All kinds of energy can be stored as potential energy.) If anything happens to break the attraction, the result can be an explosion, like that of dynamite. Atomic attractions represent chemical energy.
At the center of every atom is a nucleus. The nucleus is made up of smaller bits of matter called subatomic particles. The attractions that hold the subatomic particles together are even stronger than those that hold atoms in place. When these nuclear attractions are released, the result is a far more powerful explosion than that of dynamite. Atomic bombs owe the violence of their explosions to nuclear energy. (Sometimes nuclear energy is called atomic energy because it is obtained from atoms. But this is not a good choice of words because other forms of energy can also be obtained from atoms. For example, chemical energy also comes from atoms. But it comes from reactions outside an atom’s nucleus. “Nuclear energy,” therefore, is a more accurate name for the source of the atomic bomb’s explosion.)
Sound and light can be made to do work as sound energy and light energy. Rays of light, or light waves, are a form of radiation. Radio waves, heat, X rays, radar waves, and ultraviolet rays are other types of radiation. All these radiations, which are transmitted as waves, travel at the speed of light and represent radiant energy.
The radiant energy from the sun travels some 93,000,000 miles (150,000,000 kilometers) to the earth. Light from the sun that can be collected and converted into usable energy is called solar energy.
Work Vs. Energy
Difference Between Work And Energy