| A | B |
|---|
| motion | when the object's distance from another object is changing |
| Reference point | a place or object used for camparison to determine if something is in motion |
| International System of Units (SI) | metric sysyem, based on the number ten |
| Meter | basic SI unit of length |
| Speed | is the distance the object travels per unit of time |
| Velocity | speed in a given direction |
| Plate | upper layer of Earth-consists of more than a dozen major pieces |
| Acceleration | is that rate at which velocity changes |
