Rest (physics)
Encyclopedia
Rest in physics
refers to an object being stationary
relative to a particular frame of reference
or another object. According to the theory of relativity
it is said that an object is: at rest relative to another. For example, a train decelerates
on approach to a station and eventually stops alongside the platform. The train can be said to be at rest with respect to the station or just at rest, since in practice we do not need to specify the frame of reference if it is obvious from the context.
By Albert Einstein
's celebrated definition, two observers measure having been at rest relative to each other in a particular trial if they succeed to identify a third observer as middle
between each other.
In fact, there is nothing at absolute
rest. For example the earth is rotating around the sun which is rotating around the galaxy and so on.
The concept of relative rest is closely linked to that of inertial observers
and the statement that nothing is at absolute rest is loosely equivalent to stating that there are no frames of reference which are truly inertial. So called non inertial observers are is dealt with in the theory of general relativity
.
Physics
Physics is a natural science that involves the study of matter and its motion through spacetime, along with related concepts such as energy and force. More broadly, it is the general analysis of nature, conducted in order to understand how the universe behaves.Physics is one of the oldest academic...
refers to an object being stationary
Stationary
Stationary can mean:* In statistics and probability: a stationary process.* In mathematics: a stationary point.* In mathematics: a stationary set.* In physics: a time-invariant quantity, such as a constant position or temperature....
relative to a particular frame of reference
Frame of reference
A frame of reference in physics, may refer to a coordinate system or set of axes within which to measure the position, orientation, and other properties of objects in it, or it may refer to an observational reference frame tied to the state of motion of an observer.It may also refer to both an...
or another object. According to the theory of relativity
Theory of relativity
The theory of relativity, or simply relativity, encompasses two theories of Albert Einstein: special relativity and general relativity. However, the word relativity is sometimes used in reference to Galilean invariance....
it is said that an object is: at rest relative to another. For example, a train decelerates
Acceleration
In physics, acceleration is the rate of change of velocity with time. In one dimension, acceleration is the rate at which something speeds up or slows down. However, since velocity is a vector, acceleration describes the rate of change of both the magnitude and the direction of velocity. ...
on approach to a station and eventually stops alongside the platform. The train can be said to be at rest with respect to the station or just at rest, since in practice we do not need to specify the frame of reference if it is obvious from the context.
By Albert Einstein
Albert Einstein
Albert Einstein was a German-born theoretical physicist who developed the theory of general relativity, effecting a revolution in physics. For this achievement, Einstein is often regarded as the father of modern physics and one of the most prolific intellects in human history...
's celebrated definition, two observers measure having been at rest relative to each other in a particular trial if they succeed to identify a third observer as middle
Middle
Middle may refer to:*Centre , the point equally distant from the outer limits.-History:* Middle Ages , several meanings* Middle Stone Age, in African pre-history-Geography:* Middle Creek, various streams...
between each other.
In fact, there is nothing at absolute
Absolute time and space
Originally introduced by Sir Isaac Newton in the Philosophiæ Naturalis Principia Mathematica, the concepts of absolute time and space provided a theoretical foundation that facilitated Newtonian mechanics...
rest. For example the earth is rotating around the sun which is rotating around the galaxy and so on.
The concept of relative rest is closely linked to that of inertial observers
Inertial frame of reference
In physics, an inertial frame of reference is a frame of reference that describes time homogeneously and space homogeneously, isotropically, and in a time-independent manner.All inertial frames are in a state of constant, rectilinear motion with respect to one another; they are not...
and the statement that nothing is at absolute rest is loosely equivalent to stating that there are no frames of reference which are truly inertial. So called non inertial observers are is dealt with in the theory of general relativity
General relativity
General relativity or the general theory of relativity is the geometric theory of gravitation published by Albert Einstein in 1916. It is the current description of gravitation in modern physics...
.