| A | B |
|---|
| force | a push or a pull |
| gravity | earth's pull on all objects |
| friction | force that slows things down or makes them stop |
| rubbing | causes friction |
| inertia | objects stay still if they are still or keep moving if they are moving |
| oil | slippery substance that reduces friction |
| seat belts | hold people in place and prevent injury in car crashes |
| air bags | fill with air and help prevent injury in car crashes |
| newton | unit for measuring amount of force |
| rough surface | causes more friction, slows things down |
| smooth surface | causes less friction for things moving across it |
| chains | can be put on tires for more friction on slippery roads |
