motion vocabulary

speed

the distance traveled divided by the time it took to travel: speed = distance/time

Velocity

the speed of an object in a particular direction

Acceleration

the rate at which velocity changes over time; an object accelerates if its speed, direction, or both change

Motion

an object's change in position relative to a reference point

reference point

nonmoving or moving point from which motion is measured

Force

a push or a pull exerted on an object in order to change the motion of the object; force has size and direction