Mechanics / Electrodynamics
November 29, 2016
In Newton’s Principia the Third Law of Motion states: ‘to every action there is always opposed an equal reaction; or the mutual actions of two bodies upon each other are always equal, and directed to contrary parts.’ The Law only refers to the ‘bodies’, not other factors. The Law does not take into account the inherent characteristics, nature, compositions, flexibility, rigidity, magnitude, elasticity, distinctiveness of interacting bodies etc. The bodies may be of steel, wood, rubber, cloth, wool, sponge, spring, typical plastic, porous material, specifically fabricated material etc. The interacting bodies may be solid, liquid gas or mixture of all. For all such bodies if the action is same, then the reaction must be the same.