Representing Motion

Motion Diagram

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

Particle model

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

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

Origin

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

Position

The distance and direction from the origin to an object

Distance

The entire length of an object's path, even if the object moves in many directions

Magnitude

A measure of size

Vector

A quantity, such as position, that has both magnitude and direction

Scalar

A quantity, such as temperature or distance, that is just a number without any direction

Time Interval

the difference between two times

Displacement

A change in position, having both magnitude and direction, is equal to the final position minus the initial position

Resultant

A vector that represents the sum of two or more vectors always points from the first vector's tip to the last vector's tail.

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

Instantaneous Position

The position of an object at any particular instant in time

Average Velocity

The quotient of an object's change in position divided by the time interval during which the change occurred; for uniform motion, it is the slope of the object's position-time graph.

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

Instantaneous Velocity

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