| A | B |
|---|
| force | a push or pull |
| gravity | the force that pulls everything toward the center of earth; the force of gravitation on Earth |
| Newton | the metric unit for forces including weight |
| speed | a measure of how far something moves during a period of time |
| average speed | the measure of the total distance an object has moved divided by the total time elapsed |
| velocity | the speed of an object in a particular direction |
| friction | a force that opposes motion whenever two surfaces rub against each other |
| balanced forces | the opposite forces acting on an object that cancel each other out |
| unbalanced forces | the forces acting on an object that causes a change in velocity, making the object speed up, slow down, or change direction |
