| A | B |
|---|
| force | a push or a pull |
| gravity | the force that pulls everything toward the center of Earth: the force of gravitation on Earth |
| Newton | the metric unit for forces including weight |
| friction | a force that opposes motion whenever two surfaces rub against each other |
| balanced forces | the opposite forces acting on an object that cancel each other out |
| unbalanced forces | the forces acting on an object that cause a change in velocity, making the object spped up, slow down, or change direction |
| magnitude | the strength of a force |
| direction | which way a force is acting upon an object |
| drag | the backwards force exerted by air or water |
| exert | to push or pull something |
| elastic | when a force is exerted and at least one object is stretchy |
| elastic potential energy | the energy a stretchy object has when it is stretched or compressed |
| tension | a force that stretches something |
| compression | a force that crushes a material |
| inertia | the tendency of all objects to resist changes in motion |
| net force | the combination of all the forces acting upon an object |
| forward force | a force that is in the same direction that an object is moving |
| backward force | a force that slows down an object |
| constant forward force | a force that causes an object to speed up |
