machine
9.5 Simple Machines Simple machines are devices that can be used to multiply or augment a force that we apply often at the expense of a distance through which we apply the force. The word for machine comes from the Greek word meaning to help make things easier. Levers, gears, pulleys, wedges, and screws are some examples of machines. Energy is still conserved for these devices because a machine cannot do more work than the energy put into it. However, machines can reduce the input force that is needed to perform the job. The ratio of output to input force magnitudes for any simple machine is called its mechanical advantage MA .