| A | B |
|---|
| efficiency | expressed as a ratio of work output to work input |
| friction | force opposing motion between two surfaces that are touching |
| inertia | tendency for an object to resist a change in its motion |
| law of action and reaction | Newton's Third Law of Motion |
| mass | measures the amount of matter in an object |
| work | force x distance |
| simple machines | can be classified into two families |
| ideal mechanical advantage | number of times the effort force is multiplied |
| power | rate at which work is done |
| center of gravity | affects an object's weight distribution |
| weight | measure of the force of gravity between Earth and an object |
| How do simple machines make work easier? | changing the direction of force, transferring energy from one location to another, decrease the time it takes to do work |
| What is the double pulley? | a compound machine |
| Why does a person with leather-soled shoes not slip on carpet but will slip on a smooth polished floor? | greater friction between the carpet and the shoe soles allows forces between both surfaces to push |
| What is a joule equal to? | newton-meter |
| What are exampes of compound machines? | drill, maul, screwdriver |
| Why may an automobile slide off the road when attempting to stop on a muddy surface? | decreased friction |
| Why is a lever not 100% efficient? | the lever may bend a little and there may be friction at the fulcrum |
| What are examples of simple machines? | wedge, wheel and axle, and lever |
| How can a person produce more power in lifting a load up a flight of stairs? | decrease the time it takes to climb the stairs |
