The following sections of this BookRags Literature Study Guide is offprint from Gale's For Students Series: Presenting Analysis, Context, and Criticism on Commonly Studied Works: Introduction, Author Biography, Plot Summary, Characters, Themes, Style, Historical Context, Critical Overview, Criticism and Critical Essays, Media Adaptations, Topics for Further Study, Compare & Contrast, What Do I Read Next?, For Further Study, and Sources.
(c)1998-2002; (c)2002 by Gale. Gale is an imprint of The Gale Group, Inc., a division of Thomson Learning, Inc. Gale and Design and Thomson Learning are trademarks used herein under license.
The following sections, if they exist, are offprint from Beacham's Encyclopedia of Popular Fiction: "Social Concerns", "Thematic Overview", "Techniques", "Literary Precedents", "Key Questions", "Related Titles", "Adaptations", "Related Web Sites". (c)1994-2005, by Walton Beacham.
The following sections, if they exist, are offprint from Beacham's Guide to Literature for Young Adults: "About the Author", "Overview", "Setting", "Literary Qualities", "Social Sensitivity", "Topics for Discussion", "Ideas for Reports and Papers". (c)1994-2005, by Walton Beacham.
All other sections in this Literature Study Guide are owned and copyrighted by BookRags, Inc.
In the familiar sense, work refers to activities which require exertion. Within the scientific discipline of physics, however, the concept has a more precise definition. Here, work is the transfer of energy when a force acts on a body over some distance. For example, if a force causes something to move some distance in a straight line, then the work done by the force equals the magnitude of the force multiplied by the distance that the object traveled. When bowling, for instance, the work done by the bowler with a bowling ball is equal to the force of the swing times the distance that the ball travels along the bowling lane. Similarly, the work done by a snow plow is approximately equal to the force exerted by the plow against the snow multiplied by the length of road plowed. In another example, the work performed by the combustion of space shuttle fuel is about equal to the product of the force of the combustion against the gravitational pull on the shuttle and the distance the shuttle travels upward into the atmosphere.
When the work that is accomplished is in the same direction as the displacement, or movement, of the object, the work is said to be positive. If the force is in the opposite direction as the displacement, the work is negative. For example, pushing a door open involves positive work. The work done by the gravitational force on the space shuttle in the previous example is an example of negative work since the shuttle proceeds upward. The time component of doing work, or the rate of doing work, is called power. In order to calculate work, time is not essential, but displacement is. That is, an object must be moved from one location to another. Therefore, while it is a difficult task to hold a textbook stationary at arm's length for a period of time and energy is required, technically no work is done because there is no motion. Because the book does not gain or lose any energy from the force of the hand holding it, no energy is transferred from the hand to the book. While machines, like levers and pulleys, make tasks easier by reducing the amount of force necessary to move heavy objects, they do not change the amount of work done because the distance over which the force must be applied also changes.