We use machines to make our work easier,
and also to help us lift or move objects.
Sometimes we use simple machines by themselves,
and sometimes we combine them to create more complex
machines.
A simple machine is a machine with few or no moving parts.
There are seven types of simple machines:
-Wedge
-Inclined Plane
-Screw
-Lever
-Wheel and Axle
-Pulley
-Gears
A wedge consists of two back-to-back inclined planes. A wedge looks like an inclined plane but it works differently. It can either hold things together, as in a doorstop or nail, or it can split things apart, as in an axe or chisel.
| Screwdriver | |
Inclined Plane
| An inclined plane is a ramp. It helps us to move heavy objects more easily. We use less force but we have to apply the force over a greater distance. Friction is one problem encountered in using a ramp to move heavy objects. | Stairs, Handicap Ramps, Truck Loading Ramps, Bottom of a Bath Tub |
A screw is an inclined plane wound about a cylinder or shaft. The ridges are called the thread of a screw. The inclined plane allows the screw to move itself or to move an object or material surrounding it when rotating. To remove a screw you have to turn in the opposite direction with a screwdriver. It is very difficult to remove a screw by pulling it straight out.
| Spiral Slides, Spiral Staircase | |
The lever is a bar that turns on a point called a fulcrum. Any tool that pries something loose is a lever. Pushing down on one end of a lever results in the upward motion of the opposite end of the fulcrum.
| Snow Shovel, Wheelbarrow, Baseball Bat, Hammer | |
A wheel and axle is really two machines in one. In one way it can help roll something along. Wheels cut down on the amount of friction between what you are trying to move and the surface you're pulling it against. A wheel and axle is also like a level in the round. A door knob or a faucet on a sink are really round levels and the "fulcrum" is in the middle where the axle turns.
| Skateboards, Steering Wheel, Door Knob | |
Pulleys are wheels with grooves around the rim. This groove is for a rope or belt to move around the pulley. Pulling down on the rope can lift an object attached to the rope. Work is made easier because pulling down on the rope is made easier due to gravity.
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Gears are one way to transfer motion from one place to another. They work together in groups of two or more. One gear turns another, which may turn another, and so on. Gears are measured by counting the number of teeth they have. When the teeth of two gears fit together and one gear turns, it will cause the other gear to turn, but in the opposite direction. In any pair of gears the larger one will rotate more slowly than the smaller one, but will rotate with greater force.
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