| Term | Definition/description |
| force | any push or pull that causes an object to move, stop, or change directions |
| friction | force that opposes, or acts against, motion when two surfaces rub against each other |
| magnetism | the force of repulsion or attraction between poles of magnets |
| gravitation | force that pulls all objects in the universe toward one another |
| balanced forces | forces equal in size and opposite in direction |
| unbalanced forces | when one force is greater than its opposite force |
| acceleration | when an object starts to move, speeds up, slows down, stops, or changes direction |
| net force | combined forces |
| work | use of a force to move an object through a distance |
| power | amount of work done for each unit of time |
| machine | something that makes work seem easier by changing the size or direction of the force |
| position | an object's place, or location |
| speed | measure of the distance an object moves in a given amount of time |
| velocity | an object's speed in a particular direction |
| acceleration | any change in velocity |
| momentum | measure of how hard it is to slow down or stop an object |
| inertia | property of matter that keeps it moving in a straight line or keeps it at rest |
| Newton's first law of motion | an object at rest will stay at rest, and an object in motion will continue moving in a straight line at a constant speed until an outside force acts on it |
| Newton's second law of motion | an object's acceleration depends on the size and direction of the force acting on it and on the mass of the object |
| Newton's third law of motion | For every action, there is an equal and opposite reaction |
| orbit | the path one body in space takes as it revolves around another body |
