Position
Specifying the position of an object is essential in describing motion. In one dimension some typical ways are
x(t) is used to represent position as a function of time.
In two dimensions, either
cartesian or
polar coordinates may be used, and the use of
unit vectors is common. A position vector r may be expressed in terms of the unit vectors.
In three dimensions, cartesian or spherical polar coordinates are used, as well as other coordinate systems for specific geometries.
The vector change in position associated with a motion is called the displacement.
Index
Displacement
The displacement of an object is defined as the
vector distance from some initial point to a final point. It is therefore distinctly different from the distance traveled except in the case of straight line motion in one direction. The distance traveled divided by the time is called the speed, while the displacement divided by the time defines the average velocity.
Index