change in the position of an object (as judged by a reference point)

reference point

object or location used to judge or measure motion; considered to be stationary


rate at which distance changes

average speed

overall speed for a period of time; calculated as distance divided by time

instantaneous speed

speed at a particular instant (moment in time)

constant speed

speed that does not change


speed and direction

average velocity

overall velocity for a period of time; includes average speed and direction

instantaneous velocity

velocity at a particular instant (moment in time)

constant velocity

occurs when speed and direction do not change


1) rate at which speed or velocity changes 2) occurs whenever velocity (speed or direction) changes

positive acceleration

speeding up

negative acceleration

slowing down


device that indicates the instantaneous speed of a vehicle


another word for negative acceleration

uniform motion

occurs when there is no change in speed or direction (no acceleration); another term for constant velocity


device that indicates distance traveled by a vehicle (such as a car or bike)

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