| A | B |
|---|
| force | a push or pull |
| gravity | gravitation on Earth |
| newton | metric unit for weight or force |
| speed | a measure of how far something moves during period of time |
| average speed | a measure of the total distance an object has moved divided by the total elapsed time |
| velocity | speed of an object in a certain direction |
| friction | a force that opposes motion whenever two surfaces rub against each other |
| balanced forces | forces acting on an object that are equal in size but opposite directions; causes no change in velocity |
| unbalanced forces | forces acting on an object that are not equal in size and direction; causes a change in velocity |
| acceleration | the rate of change in velocity |
| frame of reference | something used to compare motion that you do not expect to move |
| mass | the amount of matter in an object |
| weight | the measure of the force of gravity |
| gravitation | the force that pulls all objects toward each other |
| inertia | the tendency of an object to resist a change in motion |
| net force | the combination of all the forces acting on an object |
