| A | B |
|---|
| relative motion | The change in one object's position compared with another object's position. |
| frame of reference | Objects that don't seem to move. |
| speed | The rate at which an object changes position. |
| velocity | The speed and direction an object is moving. |
| force | Any push or pull. |
| friction | A force that acts when two surfaces rub together. |
| gravity | A force that makes objects pull toward each other. |
| work | The ability to move something. |
| kinetic energy | The energy of motion. |
| potential energy | Stored energy. |
