In mechanics, motion in one dimension is defined as a change of position of an object relative to another object or with respect to a frame of reference. Motion in two-dimensional space involves the same general concepts and relationships between the position, velocity and acceleration of a moving object in one dimension simply extended to two dimensions. A classic illustration is provided by free-falling objects.

Italian astronomer and physicist Galileo Galilei's (1564-1642) study of free falling objects provided the background for English physicist and mathematician Sir Isaac Newton's (1642-1727) subsequent development of his laws of motion. Free-fall in one dimension occurs in a Cartesian plane along the vertical axis. In a two-dimensional frame of reference, motion along both horizontal and vertical axes are combined into a characteristic parabolic shape and the vertical and horizontal components of the motion are independent from each other. The dependent variables...