| A | B |
|---|
| work | the transfer of energy to an object by using a force that causes the object to move in the direction of the force |
| joule | the unit used to express energy |
| power | the rate at which work is done or energy is transferred. |
| watt | the unit used to express power; equivalent to joules per second. |
| machine | a device that helps do work by either overcoming a force or changing the direction of the applied force. |
| work input | the work done on a machine; the product of the input force and the distance through which the force is exerted. |
| work output | the work done by a machine; the product of the output force and the distance through which the force is exerted. |
| mechanical advantage | a number that tells how many times a machine multiplies force. |
| mechanical efficiency | a quantity, usually expressed as a percentage, that measures the ratio of work output to work input; it can be calculated by dividing work output by work input. |
| lever | a simple machine that consists of a bar that pivots at a fixed point called a fulcrum. |
| pulley | a simple machine that consists of a wheel over which a rope, chain, or wire passes. |
| wheel and axle | a simple machine consisting of two circular objects of different sizes; the wheel is larger of the two circular objects. |
| fixed pulley | a pulley attached to something that does NOT move and changes the force's direction. |
| movable pulley | pulley attached to the object being moved and does NOT change a force's direction. |
| Block and Tackle | A pulley system where a fixed pulley and a movable pulley are used together. |
| inclined plane | a simple machine that is a straight, slanted surface, which facilitates the raising of loads; a ramp |
| wedge | a simple machine that is made up of two inclined planes and that moves; often used for cutting. |
| screw | a simple machine that consists of an inclined plane wrapped around a cylinder. |
| compound machines | a machine made of more than one simple machine. |
