| A | B |
|---|
| force | a push or a pull exerted by one object on another |
| inertia | the tendency of a moving object to keep moving in a straight line or of any object to resist a change in motion |
| friction | a force that opposes the motion of one object moving past another |
| speed | how fast an objects position changes with time at any given moment |
| velocity | the speed and direction of a moving object |
| acceleration | change in velocity with respect to time |
| balanced forces | forces that cancel each other out when acting together on a single object |
| unbalanced forces | forces that do not cancel each other out when acting together on a single object |
| action | the force one object applies to a second |
| reaction | the force with which an object responds to an action |
| work | the use of force to move an object a certain distance |
| simple machine | a machine with few moving parts, making it easier to do work |
| lever | a simple machine made of a rigid bar and a fixed pivot point, called the fulcrum |
| fulcrum | the pivot point of a lever |
| effort arm | the part of a lever that applies force to the resistant arm |
| resistance arm | the part of a lever that applies force to the load the machine acts against |
| weight | the force of gravity between Earth and an object |
| gravity | the force of attraction between any two objects due to their mass |
