Energy, Work, and Power
ENERGY AND WORK
ENERGY AND WORK
Energy is the measure of the ability to do work or cause a change. Work is a
measure of the amount of energy required to move an object.
DEFINE the following terms:
STATE the mathematical expression for:
For a mechanical system, CALCULATE energy, work, and
Energy is defined as the measure of the ability to do work. Energy determines the capacity of
a system to perform work and may be stored in various forms. Some of the more basic
mechanical systems involve the concepts of potential and kinetic energy. Both of these terms
will be explained more fully later in this chapter. More advanced systems may include other
types of energy such as chemical, electromagnetic, thermal, acoustic, and nuclear. A piledriver
hammer performs work by virtue of its falling motion. Coal burned in a fossil-fueled power
plant is undergoing energy release by a chemical reaction. Fuel elements in a nuclear power
reactor produce energy by a nuclear reaction. For the purposes of this course, our discussions
will be limited to mechanical and thermal forms of energy (e.g., heat). It should be noted,
however, that the principles involved with energy calculations are similar for all types of energy.
Both thermal and mechanical energy can be separated into two categories, transient and stored.
Transient energy is energy in motion, that is, energy being transferred from one place to
another. Stored energy is the energy contained within a substance or object. Both of these
categories of energy will be discussed in this module.
Potential energy is defined as the energy stored in an object because of its position. An example
is the potential energy of an object above the surface of the earth in the earth's gravitational
field. Potential energy also applies to energy due to separation of electrical charge and to
energy stored in a spring, in other words, energy due to position of any force field.