# Simple Machines

## Lever

A lever is a simple machine. A lever is a board or bar that rests on a turning point. This turning point is called the fulcrum. An object that a lever moves is called the load. The closer the object is to the fulcrum, the easier it is to move.

## Wheel & Axle

The wheel and axle is another simple machine. The axle is a rod that goes through the wheel. This lets the wheel turn. It is easy to move things from place to place with wheels and axles.

## Pulley

A pulley is a wheel on an axle that is designed to support movement of a cable or belt along its circumference. Pulleys are used in a variety of ways to lift loads, apply forces, and to transmit power.

## Screw

The screw is one of the so-called "simple machines" from which many more complex machines are derived. A screw is essentially a long incline wrapped around a shaft, so its mechanical advantage can be approached in the same way as the incline.

## Wedge

The wedge is one of the so-called "simple machines" from which many more complex machines are derived. The wedge embodies the same principles as the incline in the sense that a smaller force working over a longer distance can produce a larger force acting through a small distance. As a double incline, its ideal mechanical advantage is the ratio of the depth of penetration L to the amount of separation achieved t. Note that the input force for a simple incline works along the incline, i.e., the hypotenuse of the triangle. For the wedge, the working force drives the wedge inward, and the driving force times the depth of penetration is the input work to the machine.

## Inclined Plane

The incline is one of the so-called "simple machines" from which many more complex machines are derived. By pushing an object up a slanted surface, one can move the object to height h with a smaller force than the weight of the object. If there were nofriction, then the mechanical advantage could be determined by just setting the input work(pushing the object up the incline) equal to the output work (lifting the object to height h).