A body is said to be at rest if its position with respect to its surrounding does not change. While a body is said to be in motion if its position changes with respect to its surroundings.
One-dimensional motion: When a body moves along a straight line path, its motion is said to be a one-dimensional motion. It is also called motion in a straight line or rectilinear motion.
Representation of one-dimensional motion: The path of straight-line motion is represented by a straight line parallel to the x-axis.