Inclined Plane

What’s an inclined plane? Jar lids, spiral staircases, light bulbs, and key rings. These are all examples of inclined planes that wind around themselves.  Some inclined planes are used to lower and raise things (like a jack or ramp), but they can also used to hold objects together (like jar lids or light bulb threads).

Here’s a quick experiment you can do to show yourself how something straight, like a ramp, is really the same as a spiral staircase.

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Here’s what you need to find:

• sheet of paper
• short dowel or cardboard tube from a coat hanger
• tape
• ruler

Cut a right triangle out of paper so that the two sides of the right angle are 11” and 5 ½” (the hypotenuse – the side opposite the right angle – will be longer than either of these). Find a short dowel or use a cardboard tube from a coat-hanger.  Roll the triangular paper around the tube beginning at the short side and roll toward the triangle point, keeping the base even as it rolls.

Notice that the inclined plane (hypotenuse) spirals up as a tread as you roll. Remind you of screw threads?  Those are inclined planes. If you have trouble figuring out how to do this experiment, just watch the video clip below:

 
Download Student Worksheet & Exercises

Inclined planes are simple machines. It’s how people used to lift heavy things (like the top stones for a pyramid).

Here’s another twist on the inclined plane: a wedge is a double inclined plane (top and bottom surfaces are inclined planes). You have lots of wedges at home: forks, knives, and nails just name a few.

When you stick a fork in food, it splits the food apart. You can make a simple wedge from a block of wood and drive it under a heavy block (like a tree stump or large book) with a kid on top.

Exercises

1. What is one way to describe energy?
   1. The amount of atoms moving around at any given moment
   2. Electrons flowing from one area to another
   3. The ability to do work
   4. The square root of the speed of an electron
2. Work is when something moves when:
   1. Force is applied
   2. Energy is used
   3. Electrons are lost or gained
   4. A group of atoms vibrate
3. Name two simple machines:
4. Name one example of a simple machine:

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