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Basic Concepts

Simple Machines


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Simple Machines

Machines help us do work. They never increase the amount of work done, but they can make work easier by requiring less force, or they may increase the amount of motion that work produces. When machines make work easier, they are said to increase mechanical advantage. Mechanical advantage compares the amount of force put into a device to the amount of force the device puts out. Sometimes this is stated as the ratio of the Resistance to the Effort.

Simple machines are the basic components from which more complicated ones are built. All simple machines can be classed in one of two groups:

  • The Lever Group -- levers, wheels and axles, and pulleys. These devices make use of rotation about a pivot point to alter mechanical advantage.
  • The Wedge Group -- inclined planes, wedges, screws. These simple machines use the idea that a long trip up a gentle slope results in the same accomplishment with less effort than a short climb up a steep cliff.

The following sites provide colorful and interesting introductions to the elements of simple machines:
COSI Simple Machines On-line Exhibit
At COSI they have developed a number of on-line explorations for students to learn about various science phenomena. This exhibit includes animated descriptions of simple machines and several activities through which students are led to identify simple machines in various applications.
Elements of Simple Machines
This site from the Boston Museum of Science's exhibit on Leonardo da Vinci explains the operation of simple machines and other devices derived from them such as gears and chain drives in preparation for an activity in which students analyze gadgets of all sorts to discover the simple machines from which they are built.
Franklin Institute's presentation on Simple Machines
This page contains images and descriptions of simple machines and their applications. Many descriptions are linked to extra information and examples of machines constructed from Lego building blocks.

Last updated Tuesday, March 12, 2002
© 2002 All rights reserved   Tom Stork
Background adapted from "Design for a flying machine," a drawing by Leonardo da Vinci