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average speed

how fast an object is moving, is the absolute value of the slope of an object's position-time graph

average velocity

the change in position, divided by the time during which the change occured, is the slope of an object's position-time graph

constant velocity

a speed that does not change how fast it is, or the direction that it is in

coordinate system

a system used to describe motion that gives the zero point location of the variable being studied and the direction in which the values of the variable increase

displacement

a change in position having both magnitude and direction; is equal to the final position minus the initial position

distance

a scalar quantity that describes how far an object is from the origin

instantaneous position

the position of an object at any particular instant in time

instantaneous velocity

a measure of motion that tells the speed and direction of an object at a specific instant in time

magnitude

measure of size

motion diagram

a series of images showing the positions of a moving object taken at regular (equal) time intervals

origin

the point at which both variables in a coordinate system have the value zero

particle model

a simplified version of a motion diagram in which the moving object is replaced by a series of single points

position

the separation between an object and the origin; it can be either positive or negative

position vs. time graph

a graph that can be used to determine an object's velocity and position, as well as where and when two objects meet, by plotting the time data on a horrizontal axis and the position data on a vertical axis

scalar quantity

such as temperature or distance, that are just numbers without any direction

slope of a position vs. time graph

indicates both the magnitude and direction, indicates the average velocity of the object and not its speed

speed

relative rapidly in moving, going, etc. rate of motion or progress (distance/time)

time interval

the difference between two times

vector quantity

such as position, that have both magnitude and direction