| A | B |
|---|
| force | a push or pull exerted on an object |
| net force | the overall force on an object when all the individual forces acting on an object are added together |
| unbalanced force | a nonzero net force, which changes an object's motion |
| balanced forces | equal forces acting on an object in opposite directions |
| inertia | the tendency of an object to resist any change in its motion |
| mass | the amount of matter in an object |
| newton | a unit of measure that equals the force required to accelerate one kilogram of mass at 1 meter per second per second |
| friction | the force that one surface exerts on another when the two rub against each other |
| sliding friction | friction that occurs when one solid surface slides over another |
| rolling friction | friction that occurs when an object rolls over a surface |
| gravity | the force that pulls objects toward each other |
| free fall | the motion of a falling object when the only force acting on it is gravity |
| projectile | an object that is thrown |
| air resistance | the fluid friction experienced by objects falling through the air |
| terminal velocity | the maximum velocity a falling object can achieve |
| weight | the force of gravity on an object at the surface of a planet |
| momentum | the product of an object's mass and velocity |
| law of conservation of momentum | the rule that the total momentum of objects in an interaction does not change |
| fluid friction | Friction that occurs as an object moves fthrough a fluid |
