Rest frame

The rest frame of a rigid body is a system of reference in which it rests, that is, in which all of its coordinates remain constant. If the coordinate origin at the center of the body, it is also a focal point for this system.

Only for uniformly moving body the rest frame is an inertial frame. In general, however, the acceleration is not zero, and the rest system is an accelerated frame of reference.

For example, the rest frame of the Earth's surface rotates with the Earth's rotation, which leads to centrifugal and Coriolis forces, with significant influence ( among others ) on ocean currents and climate.

Rest systems as observers in special relativity theory

Rest systems of points mentioned in the special theory of relativity observers. Time as it passes the observer is called the proper time. The relationships between relatively stationary objects directly serve to define the measured variables as distance, duration and indirectly, therefore, to define it based metrics such as speed, acceleration, angle, angular velocity, curvature etc.

Limited rest systems and their relationships

The demand for reciprocity rest can be filled with parties, determine the still beyond relations with each other, eg that four of them with each other are. The corresponding rest frame is in such a case a ( subset of a ) level represents the members of various such tranquility systems turn not rest necessarily to each other, or they do not move necessarily opposed to each other ( uniform or otherwise), but there is also the possibility that they are mutually rigid.

Preparation of inertial frames on the basis of given rest systems

If the members of a given idle system (or their codes) are assigned coordinate values ​​and these affine with respect to the existing distances (or times ) are the coordinate system thus formed is called an inertial frame.

• Theoretical Mechanics
• Relativity theory