| A | B |
|---|
| force | a push or a pull |
| newton | SI unit to measure a force |
| unbalanced forces | forces that can cause an object to start moving, stop moving, or change direction |
| net force | combination of forces acting on an object |
| balanced forces | equal forces acting on an object in opposite directions |
| friction | the force that 2 surfaces exert on each other as they rub against each other |
| static friction | friction that acts on objects that are not moving |
| rolling friction | friction that occurs when an object rolls across a surface |
| sliding friction | friction that occurs when 2 solid surfaces slide over each other |
| gravity | force that pulls objects toward each other |
| air resistance | type of fluid friction that happens when an object falls through the air |
| mass | the measure of the amount of matter in an object |
| projectile | an object that is thrown |
| free fall | when the only force acting on an object is gravity |
| terminal velocity | greatest velocity a falling object reaches |
| fluid friction | when a solid object moves through a fluid |
| weight | the force of gravity on a person |
