| A | B |
|---|
| work | The action that results when a force causes an object to move in the direction of the force; W=Fxd |
| joule | The unit used to express word and energy; equivalent to the newton-meter (Nxm) |
| power | The rate at which work is done; P=W/t |
| watt | The unit used to express power; equivalent to joules per second (J/s) |
| machine | A device that helps make work easier by changing the size or direction (or both) of a force |
| work input | The work done on a machine; the product of the inupt force and the distance thorough which it is exerted |
| work output | The work done by a machine; the product of the output force and the distance through which it is exerted |
| mechanical advantage | A number that tells how many time a machine multiplies force; can be calculated by dividing the output force by the input force |
| mechanical efficiency | A comparison expressd as a percentage of a machine's work output with the work input; can be calculated by dividing work output by work input and then mulitplying by 100 |
| lever | A simple machine consisting of a bar that pivots at a fixed point, called a fulcurm; there are three classesof levers, based on where the input force,. Output force, and fulcrum are placed in relation to the load: first class levers, second class levers, and third class levers |
| inclined plane | A simple machine that is a straight, slanted surface; a ramp |
| wedge | A simple machine that is a double inclined plane that moves; a wedge is often used for cutting |
| screw | A simple machine that is an inclined plane wrapped in a spiral |
| wheel and axle | A simple machine consisting of two circular objects of different sized; the wheel is the larger of the two circular objects |
| pulley | A simple machine consisting of a grooved wheel that holds a rope or a cable; there are two kinds of pulleys- fised and moveable |
| compound machine | Machine that is made of two or more simple machines |
