| A | B |
|---|
| acceleration | a change in an object's speed or direction |
| contact force | a force that must touch an object to change its speed and/or direction |
| force | a push or pull that causes something to change its motion |
| friction | a force that occurs when two things move past each other and rub together |
| gravity | a force that acts without physical contact to pull two objects toward each other |
| inertia | the tendency of objects to keep doing what they are doing |
| net force | the amount by which the opposing forces acting on an object are unequal |
| newton | the metric unit used to measure force or weight |
| Newton's first law of motion | if the force acting on an object are balanced, the object will continue doing what it is doing |
| Newton's second law of motion | the acceleration of an object is related to the net force acting on it and the mass of the object |
| Newton's third law of motion | for every action there is an equal and opposite reaction |
| noncontact force | a force that acts on an object to change its speed or direction from a distance |
| normal force | the force that pushes up to support the weight of an object |
