Work  The product of the force and distance when a force is used to move an object

Joule  A unit of work equal to one Newton- meter

Machine  A device that changes the amount of force exerted; the distance over which force is exerted, or the direction in which force is exerted.

Input force  The force exerted on a machine

Output force  The force exerted on an object by a machine

Mechanical advantage  The number of times the force exerted on a machine is multiplied by the machine

Efficiency  The percentage of the input work that is converted to output work

Actual mechanical advantage  The mechanical advantage that a machine provides in a real situation

Ideal mechanical advantage  The mechanical advantage that a machine would have without friction

Inclined plane  A simple machine consisting of a flat surface with one end higher than the other

Wedge  A simple machine consisting of a device that is thick at one end and tapers to a thin edge at the other

Screw  A simple machine consisting of an inclined plane wrapped around a central cylinder to form a spiral

Lever  A simple machine consisting of a rigid object that pivots about a fixed point

Fulcrum  The fixed point around which a lever pivots

Wheel and axle  A simple machine consisting of two circular or cylindrical objects that are fastened

Pulley  A simple machine consisting of a grooved wheel around which is wrapped around a rope, cable, or chain

Compound machine  A device that combines two or more simple machines