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Earth ramp going steeply uphill in a dry landscape: an inclined plane

An inclined plane: Earth ramp to the fortress at Masada (Thanks to

What is an inclined plane?

An inclined plane is any slope or ramp, like a wheelchair ramp or a slide. The ramp makes it easier to lift something heavy, like a rock.

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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.

Mechanical advantage of inclined planes

What if you make the ramp steeper? Then you’ll have a shorter distance. But it will be harder to push the rock. (You’ll need more force). What if you make the ramp less steep? Then 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.

Why is it called a “plane”?

We call it an “inclined plane” because it is a plane – a flat surface – and it is inclined – sloped, not level. Inclined planes also let you control how fast something goes downhill. Objects fall faster on a steeper ramp.

What is a plane?
How does gravity work?

You could just drop the thing, and let gravity pull it to earth. But maybe you’d like to go slower. Maybe you enjoy the speed from going down a slide, but you might break your arm if you just fell from the top of the slide straight down.

A wheelchair ramp in a city: a kind of inclined plane

A wheelchair ramp is a kind of inclined plane

Animals use inclined planes

All kinds of animals use inclined planes when they choose their path up or down a steep hill. Some animals also make their own inclined planes.  Ants, for example, use inclined planes in building their anthills.

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A model of a typical house (from Egypt)

History of the inclined plane: A model of a typical house (from Bronze Age Egypt) with a staircase going up to the second floor.

Inclined planes and the Pyramids

People have used inclined planes since even before they were people, about 200,000 years ago. By the time of Old Kingdom Egypt, about 2500 BC, people were building their own earth ramps. They used those ramps to move heavy stones for the Pyramids.

More about the Pyramids

Staircases are inclined planes

The first staircases (a special 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 wheelchair ramp is also an inclined plane. It makes it easier to get your wheelchair uphill and downhill.

Houses in ancient Egypt

A zipper

A zipper is a kind of wedge – or a lot of little wedges!

Wedges and inclined planes

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

More about wedges
And about screws

Looking for a second source to cite about inclined planes? Check out Scholastic’s explanation.

Learn by doing: build a ramp from blocks and see how fast objects slide down it when it is steep or when it is less steep.
More about wedges
And specifically about screws
More about simple machines

Bibliography and further reading about simple machines:

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