| A | B |
|---|
| force | push or pull |
| net force | overall force |
| unbalanced force | nonzero net force |
| balanced forces | equal,opposite forces on one object |
| inertia | resistance to change in motion |
| mass | amount of matter in an object |
| newton | 1 kg*m/s/s (mass times acceleration) |
| friction | force between touching surfaces |
| sliding friction | force between sliding surfaces |
| rolling friction | force between flat and round surfaces |
| fluid friction | force between a solid and a fluid |
| gravity | pulling force of Earth |
| free fall | only force is gravity |
| projectile | object that is thrown |
| air resistance | fluid friction on falling objects |
| terminal velocity | maximum falling velocity |
| weight | force of gravity on an object |
| momentum | mass times velocity |
| conservation of momentum | total momentum in a system stays constant |
| centripetal force | force that causes an object to curve |
