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Re: Physics definition of work



You can easily show that a screw is actually an inclined plane wrapped around
a rod such as a pencil or a dowel. Here is how you can demonstrate it in a
matter of minutes.

Cut an 8 1/2 by 11 inch paper diagonally into two right triangles Outline
the hypotenuse of one triangle with a dark colored marker. Lay the triangle
on a flat surface with the marked side down. Place a pencil along the short
leg of the triangle and wrap the paper around the pencil so that the base of
the triangle, the long side, remains even as the paper is rolled. The
assembly will look like a screw. The spirals or threads that form are really
the length of the inclined plane. You can determine the mechanical
advantage (MA) of the paper screw by counting the number of threads or
spirals per inch and compute from this, the distance between the threads or
spirals (the pitch) or you may use calipers to measure the pitch directly.
Measure the diameter of the paper screw and use it to determine the MA by
taking the ratio of Pi times the diameter of the paper screw (effort
distance) to the pitch (resistance distance).

Try it. It's easy and costs next to nothing and it is effective.

Greg Darakjian
Anaheim High School
811 W. Lincoln Ave
Anaheim, CA 92805