Unit 9 Vocabulary: Work, Power, Simple Machines

Work

A measure of the energy required to exert force over a distance

lever

A lever is a simple machine that consists of a bar that pivots on a fulcrum.

wheel and axle

A wheel and axle is a simple machine that consists of two attached circular objects of different sizes.

Joules (J)

The SI (metric) unit for work (same as the unit for energy).

Watt (Joule per second)

The SI (metric) unit for power

Power

The rate(how fast) at which work is done. Work/Time

Screw

An inclined plane wrapped around a cylinder

Mechanical efficiency

a comparison of a machine's work output with the work input

Mechanical advantage

the number of times a machine increases a force exerted on it

Machine

A device that makes work easier (not lesser) by changing the size and/or direction of the force applied

Input

The force you apply (input force) or the work you do on a machine (input work)

Simple machine

A nonpowered device that makes work easier (not lesser) by changing the size and/or direction of the force applied