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Work, Power
| Question | Answer |
|---|---|
| work | occurs when an object moves in the direction of a force |
| joule | used to express work and energy; equivalent to the newwton-meter |
| power | the rate at which work is done |
| watt | used to express power; equivelant to joules per second |
| machine | a device that helps make work eaiser by changing the size or direction of a force |
| work input | the work is done by machine; tje product of the input force and the distance through which it is exerted |
| work output | the work is done by machine; the product of the output force and the distance through which it is exerted |
| mechanical advantages | a number that tells how many times a machine multiplies force; can be calculated by dividing work output by work input then x 100 |
| mechanical efficiency | a comparison-expressed as a percentage-of a machine's work output with the work input; can be calculated by dividing work output by work input then x 100 |
| lever | a simple machine consisting of a bar that pivots at a fixed point, called a fulcrum |
| incline plane | a simple machine that is a straight, slanted surface; a ramp |
| pulley | a simple machine consisting of a grooved wheel that holds a rope of cable |
| wheel and axle | a simple machine consisting of two circular objects of different sizes; the wheel is the larger of the two objects |
| wedge | a simple machine that is a double incline plane that moves |
| screw | a simple machine that is an incline plane wrapped in a spiral |
| compound machine | a machine that is made of two or more simple machine |
| energy | the ability to do work |
| kinetic energy | the energy of motion; kinetic energy depends on speed and mass |
| potential energy | the energy of position or shape |
| mechanical energy | the total energy of motion and position of an object |
| what are five examples of work being done? | pushing a cart, bowling, lifting weights, pushing a book, eating |
| what are five examples of work not being done? | walking, doing homework, standing, holding a book, carrying bags |
| what is the equation used to calculate work and what units are used to express the amount of work being done? | W = F x D |
| how are work and power alike? how are they different? | power is the rate work is done. when you do work you use power, but power will get a job done faster |
| what is the equation used to calculate power and what units are used? | P = W/T |
| what is the scientific definition for a machine? | it is a device that helps make work easier by changing the size or direction of a force |
| what are some machines that you can find in a classroom? | Scissors, screw, pencil sharpener, |
| what is the force-distance trade-off that occurs when machines are used? | when a machine changes the size of the force, the distance through which the force is exerted must also change force or distance can increase, but not together |
| are the input force and the output force ever different amounts if force? | ? |
| are the work input and the work output ever different amounts of work? | work output is never greater than work input |
Created by:
gymfin4me
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