| Term | Definition |
| velocity | describes both speed and direction of an object |
| acceleration | the rate of change of velocity |
| balanced forces | forces on an object that are equal in size and opposite in direction |
| inertia | the tendency of an object to resist any change in its motion |
| friction | the force that opposes motion between two surfaces that are touching each other |
| gravity | force exerted by every object in the universe on every other object |
| weight | measure of the force of gravity on an object |
| air resistance | the force air exerts on a moving object |
| terminal velocity | the highest velocity that will be reached by a falling object |
| projectile | anything that's thrown or shot through the air |
| centripetal force | a force acting toward the center of a curved of circular path |
| speed | rate of change in position |
| net force | type of force that changes the motion of an object |
| instantaneous speed | the rate of motion at any given moment |
| force | push or pull exerted on an object |
| constant speed | speed that does not change |
| average speed | the total distance traveled divided by total time of travel |