Mechanics / Electrodynamics
April 17, 2018
Newton’s law stated in the last decades of seventeenth century. The impact of this fact can be easily realized. Today a law is regarded as established, if predictions from mathematical equations are experimentally confirmed. The mathematical equations are expressed in terms of physical quantities such as velocity, acceleration force etc. For examples velocity has units (m/s) and dimensions (M^0 LT^-1). But now as such ‘Action’ and ‘Reaction’ are not regarded as physical quantities. These are philosophically used in physics . Newton expressed ‘action’ and ‘reaction’ in first two examples as push or pull (now regarded as force), and third example in terms of change in momentum (mathematically comes out velocity).