# Simple machine

A simple machine is a device that can change the direction or the magnitude of a force, or the point where it is applied. This is done so that the force can be used to do work. All mechanical machines are made by combining simple machines.

There are five basic "simple machines", as defined by Renaissance scientists:[1]

1. The lever (also called a rope or staff) can move the point at which a force is applied and may also change the magnitude and direction of the force.
2. The wheel change the direction in which the force is applied
3. The pulley changes the point where a force is applied, and may also change its magnitude and direction.
4. The inclined plane (also called a wedge)
5. The screw that converts rotational motion to linear motion, and a rotational force to a linear force.

The use of simple machines can be traced back to homo habilis (the first humans to use tools), but certain animals other than man also use them.

A compound machine is made up of two or more simple machines.

## References

1. Anderson, William Ballantyne (1914). Physics for technical students: mechanics and heat. New York, USA: McGraw Hill. pp. 112–122. Retrieved 2008-05-11.