| A | B |
|---|
| acceleration | an object that is speeding up, slowing down, or changing directions |
| force | push or pull that gives energy to an object |
| frame of reference | background or point that is assumed to be stationary and is used for comparison when motion is described |
| friction | force that acts in the opposite direction of motion; will cause an object to slow down and finally stop |
| gravity | force of attraction that depends on the mass of two objects and the distance between them |
| inertia | property of matter that tends to resist any change in motion |
| Law of Conservation of Energy | law that states that energy is neither created nor destroyed by ordinary means |
| Law of Universal Gravitation | law that states that all objects in the universe attract each other by the force of gravity |
| momentum | mass of an object times its velocity |
| motion | change in position in a certain amount of time |
| speed | rate at which an object moves |
| velocity | description of speed in a given direction |
| speed = | distance divided by time |
| acceleration = | final velocity-original velocity divided by time |
| momentum = | mass times velocity |
| most common frame of reference | The Earth |
| deceleration | negative acceleration |
| combining velocites | when two objects are moving in the same direction, their velocities add together |
| subtraction velocities | when objects are moving in opposite directions, their velocities are subtracted |
| conservation of momentum | the total momentum of any group of objects remains the same unless outside forces act on the objects |
