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The Concept of Energy

Reduced to simplest terms, the universe is nothing more than a series of energy exchanges. As in much of physics, the concept of energy is easy to understand, but difficult to express and work with.

Energy = The ability to cause change.

Notice the simplicity of this definition. If something has the ability to cause a change in the physical or chemical properties of another object it has energy. If we restrict our study to mechanical energy, then we consider the changes in the state of motion of an object.

There are different classifications of energy, usually named for the source of the force involved; mechanical, gravitational, electrical, nuclear, etc. Within each of these areas the energy is further classified as either potential or kinetic energy.

Potential energy - Energy due to an object?s position.

Kinetic energy

The specifics which determine the amount of each of these types of energy are determined by the situations they are in, but in general, potential energy is determined by where an object is and the kinetic energy is determined by how much motion it has.

The chemical potential energy of a substance depends on the bond structure within the material, the nuclear potential energy of a material depends on the composition if its nuclei, the mechanical potential energy of a wind-up car depends on the state of its internal spring.

The kinetic energy of a gas depends on the motion of its molecules, the kinetic energy of a galaxy depends on the movement of its constituent stars, the mechanical energy of a truck depends on its mass and velocity.

You can't see energy, which makes it a little tough to comprehend, but you can see, feel, and measure when the energy of an object changes. It is by these changes that we can get a handle on where the energy is and where it is going.

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