Absolute value
magnitude of a number, regardless of sign
Average speed
the distance traveled divided by the time taken to travel that distance; for uniform motion, it is the absolute value of the slope of the object's position-time graph
Average velocity
the ratio of an object's change in position to the time interval during which the change occurred; for uniform motion, it is the slope of the object's position-time graph
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
Dimension
extension in a given direction; one dimension is along a straight line; three dimensions are height, width, and length
Displacement
a change in position having both magnitude and direction; is equal to the final position minus the initial position
Distance
the entire length of an object's path, even if the object moves in many directions
Instantaneous position
the position of an object at any particular instant
Instantaneous velocity
a measure of motion that tells the speed and direction of an object at a specific instant
Intersection
a point where lines meet and cross
Magnitude
a measure of size
Model
A representation of an idea, event, structure, or object to help people better understand it.
Motion diagram
a series of images showing the positions of a moving object 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 distance and direction from the origin to the object
Position-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 horizontal axis and the position data on a vertical axis
Resultant
a vector that represents the sum of two other vectors; it always points from the first vector's tail to the last vector's tip
Scalar
a quantity, such as temperature or distance, that is just a number without any direction
Time interval
the difference between two times
Vector
a quantity, such as position, that has both magnitude and direction