| A | B |
|---|
| work | force that occurs over a given distance |
| 746 watts | one horsepower |
| power | rate at which work is done |
| units that power is measured in | watts (W) |
| units that work is measured in | joules (J) |
| equation for work | W = f x d |
| equation for power | P = W / t |
| simple machines | devices that make it easier to do work |
| mechanical advantage | how much a machine helps with the work |
| mechanical advantage has units of | nothing ( ) |
| equation for mechanical advantage | MA = output force / input force or input distance / output distance |
| screw | inclined plane family example |
| pulley | lever family example |
| output force and input force in the same direction | decreases input force |
| output force and input force in opposite directions | increases input force |
| compound machine | machine made of more than one simple machine |
| potential energy | stored energy |
| elastic potential energy | pulled back sling-shot |
| gravitational potential energy | ball on the edge of a cliff |
| kinetic energy | energy in motion |
| equation for potential energy | PE = mgh |
| equation for kinetic energy | KE = 1/2 mv^2 |
| mechanical energy | sum of all potential and kinetic energy |
| energy we find in food called | Calorie |
| one Calorie equals how many joules? | 4186 J |
| law of conservation of energy | energy cannot be created or destroyed |
| efficiency | ratio of useful work output to work input |
| equation for efficiency | efficiency = useful work output / work input |
