Six Simple Machines
By: Robyn Hamilton
Wheels, Axles, and Levers
When using wheels and axles, you have an axle that wheels are on like on a bus or in a car. When you press the gas pedal, it spins the axle and makes the wheels turn. A lever is a simple machine that uses a variable distance to multiply force, or to redirect existing forces. With a lever, the force exerted by gravity on a weight can be used to lift another weight. By varying the distance between a lever's ends and its fulcrum, a heavy object can be lifted to a short distance by a smaller force moving a longer distance.
Inclined Plane and Pulley
An inclined plane reduces the force necessary to raise a given distance. The reduction is related to the sine of the angle of inclination of the slope. A pulley is like a wheel with a string going on one side going up and around the down the other side. When you pull one side, it lifts the load that is on the other side up and when you let go, the load drops.
Wedge and Screw
A wedge is a portable inclined plane, used either to separate two objects, or two portions of an object, lift an object, or hold an object in place, by the application of force to the wide end, which the wedge converts to force perpendicular to the inclined surfaces. The mechanical advantage of a wedge depends on the ratio of its length to its thickness. Where a short wedge with a wide angle does the job faster, it requires more force than a long wedge with a smaller angle. A screw changes the direction of force from around in a circle to down. The tool screw was named after this simple machine.