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WEM
Work, Energy and Machines
| Term | Definition |
|---|---|
| even if a large force is exerted on an object, no work is performed if | the object does not move |
| power | the rate at which work is done |
| effort and resistance | two forces always involved in using a machine are |
| efficiencey is | the comparison between work output and work input |
| mechanical advantage | decreasing the slant of an incline plane increases its |
| neither force nor distance is muliplied by a(n) | fixed pulley |
| a gear in a watch is an example of a(n) | wheel and axle |
| work equals | force X time |
| joule or newton-meter is | the unit of work in the metric system i |
| power | work divided by time |
| machine | an instrument that makes work easier |
| work input | the work that goes into a machine |
| work output | the work done by the machine |
| machines make work easier because | they change either the size or the directions of the force put into a machine |
| wedge | an incline plane that moves |
| screw | an inclined plane wapped around a central bar, or cylinder, to form a spiral |
| lever | rigid bar that is free to pivot, or move about a fixed point |
| fulcrum | the fixed point about which a lever rotates |
| first class lever | the fulcrum is located between the resistance force and the effort force |
| second class lever | the resistance force is located between the fulcrum and the effort force |
| third class lever | the elfort force is located between the resistance force and fulcrum |
| pulley | a rope, belt, or chain wrapped around a grooved wheel |
| wheel and axle | machine made up of two circular objects of different sizes----in a sense, a wheel in a wheel |
| compound machine | a combination of two or more simple machines |
| power | rate at which work is done |
| watt | the unit of power in the metric system |