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Kinematics, the theory of the motion of bodies. Kinematics deals with the mathematical
description of motion without considering the applied forces. The quantities position,
path, time, velocity and acceleration play central roles.
1.1 Description of motion
Motion, the change of the position of a body during a time interval. To describe the motion,
numerical values (coordinates) are assigned to the position of the body in a coordinate
system.Thetime variation of the coordinates characterizes the motion.
Uniform motion exists if the body moves equal distances in equal time intervals. Op-
posite: non-uniform motion.
1.1.1 Reference systems
1. Dimension of spaces
Dimension of a space, the number of numerical values that are needed to determine the
position of a body in this space.
■ A straight line is one-dimensional, since one numerical value is needed to fix the
position; an area is two-dimensional with two numerical values, and ordinary space
is three-dimensional, since three numerical values are needed to fix the position.
■ Any point on Earth can be determined by specifying its longitude and latitude. The
dimension of Earth’s surface is 2.
■ The space in which we are moving is three-dimensional. Motion in a plane is two-
dimensional. Motion along a rail is one-dimensional. Additional generalizations are
a point, which has zero dimensions, and the four-dimensional space-time continuum
(Minkowski space), the coordinates of which are the three space coordinates and one
time coordinate