The special

**principle of relativity**states that physical laws should be the same in every inertial frame of reference, but that they may vary across non-inertial ones. This**principle**is used in both Newtonian mechanics and the theory of special**relativity**.In the theory of general

**relativity**, the**equivalence principle**is the equivalence of gravitational and inertial mass, and Albert Einstein's observation that the gravitational "force" as experienced locally while standing on a massive body (such as the Earth) is the same as the pseudo-force experienced by an observer in a non-inertial (accelerated) frame of reference**relativity**, wide-ranging physical theories formed by the German-born physicist Albert Einstein. With his theories of special**relativity**(1905) and general**relativity**(1915), Einstein overthrew many assumptions underlying earlier physical theories, redefining in the process the fundamental concepts of space, time, matter, energy, and gravity. Along with quantum mechanics,**relativity**is central ...V. The

**Principle****of Relativity**(in the Re-stricted Sense) ..... 14 VI. The Theorem of the Addition of Velocities employed in Classical Mechanics ... 19 VII. The Apparent Incompatibility of the Law of Propagation of Light with the**Prin-ciple****of Relativity**..... 21 VIII. On the Idea of Time in Physics .... 25 IX. The**Relativity**of Simultaneity .....**General relativity**follows from Einstein’s**principle**of equivalence: on a local scale it is impossible to distinguish between physical effects due to gravity and those due to acceleration. Gravity is treated as a geometric phenomenon that arises from the curvature of space-time .www.cambridge.org

**Archimedes’ Principle**Applications. Following are the applications of**Archimedes’ principle**: Submarine: The reason why submarines are always underwater is that they have a component called ballast tank which allows the water to enter making the submarine be in its position underwater as the weight of the submarine is greater than the ...