Rest ( physics ) - Wikipedia Rest ( physics ) This article 's tone or style may not reflect the encyclopedic tone used on Wikipedia. See Wikipedia 's guide to writing better articles for suggestions. ( January 2013 ) Rest, in physics, refers to an object being stationary relative to a particular frame of reference or another object. When the position of a body with respect to its surroundings does not change with time it is said to be `` at rest ''. According to the theory of relativity, it is said that an object is `` at rest relative to '' another. For example, a train decelerates approaching a station and eventually comes to rest alongside the platform. The train can be said to be `` at rest with respect to the station '', or, as the correct frame of reference is usually implicit and / or provided by context, simply `` at rest ''. Given an inertial frame of reference, Newton 's first law of motion states that an object at rest will remain at rest, while the motion of a moving object will remain unchanged until acted upon by an external force. An object at rest, therefore, can be described as without velocity and acceleration -- although, according to relativity, an object is either at rest or in motion relative to other moving objects. 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 addressed by the theory of general relativity. In reality, there is nothing at absolute rest. For example, Earth 's gravitation constantly pulls objects toward its surface, while Earth is one of the objects the Sun constantly pulls towards itself, causing it to orbit the Sun ; the Sun, in turn, orbits the center of the Milky Way ; and so on. Two or more than two objects are said to be at rest, if its position with respect to each other is not changing or moving with uniform velocity with respect to each other. Rest and motion are relative term. References Jump up ^ `` Newton 's first law ''. The Physics classroom. 2014 - 03 - 20. Jump up ^ `` Newton 's First Law of Motion ''. www.grc.nasa.gov. Retrieved 2016 - 02 - 09. This classical mechanics - related article is a stub. You can help Wikipedia by expanding it. Retrieved from `` https://en.wikipedia.org/w/index.php?title=Rest_(physics)&oldid=784890798 '' Categories : Concepts in physics Classical mechanics stubs Hidden categories : Wikipedia articles needing style editing from January 2013 All articles needing style editing All stub articles Talk About Wikipedia Español Français हिन्दी Bahasa Melayu नेपाल भाषा Português Sicilianu Suomi 中文 Edit links This page was last edited on 10 June 2017, at 15 : 25. Text is available under the Creative Commons Attribution - ShareAlike License ; additional terms may apply. By using this site, you agree to the Terms of Use and Privacy Policy. Wikipedia ® is a registered trademark of the Wikimedia Foundation, Inc., a non-profit organization. About Wikipedia

Question: when can we say that an object is at rest
Answer: When the position of a body with respect to its surroundings does not change with time