Inclined Planes - Simple Machines answers questions
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Inclined Plane

Masada ramp
Earth ramp to the fortress at Masada
(Thanks to

An inclined plane is any slope or ramp, like a wheelchair ramp or a slide. It makes it easier to lift something heavy, like a rock. Instead of lifting the rock straight up, you can push it a greater distance, but with less force. The amount of work remains the same. Work is force x distance, so if you increase the distance the rock moves, you can decrease the amount of force you need.

If you make the ramp steeper, you'll have a shorter distance, but it will be harder to push the rock (you'll need more force). If you make the ramp less steep, it will have to be longer, but it will be easier to push the rock. Either way, it's the same amount of work in the end, but you have the choice of doing easier work for a longer time, or harder work for a shorter time.

We call it an "inclined plane" because it is a plane - a flat surface - and it is inclined - sloped, not level. All kinds of animals use inclined planes when they choose their path up a steep hill, and people have used them since there first were people, about 200,000 years ago. By the time of Old Kingdom Egypt, about 2500 BC, people were building their own earth ramps to move heavy stones for the Pyramids. The first staircases (a kind of inclined plane, because stairs make it easier to go up than if you had to jump) also go back to the Bronze Age.

A wedge is a particular kind of inclined plane (a wedge is two inclined planes back to back), and a screw is another kind.

Bibliography and further reading about simple machines:

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Professor Carr

Karen Eva Carr, PhD.
Assoc. Professor Emerita, History
Portland State University

Professor Carr holds a B.A. with high honors from Cornell University in classics and archaeology, and her M.A. and PhD. from the University of Michigan in Classical Art and Archaeology. She has excavated in Scotland, Cyprus, Greece, Israel, and Tunisia, and she has been teaching history to university students for a very long time.

Professor Carr's PSU page

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