Mass in special relativity what causes these particles to be termed "massless." However, even massless particles have a relativistic mass, which varies with their observed energy in various frames of reference, The invariant mass is the ratio of four-momentum (the four-dimensional generalization of classical momentum) to four-velocity: and is also the ratio of four-acceleration to four-force when the rest mass is constant. The four-dimensional form of Newton's second law is: The relativistic expressions for "E" and "p" obey the relativistic energy–momentum relation: where the m is the rest mass, or the invariant mass for systems, and "E" is the total energy. The equation is
N. S. Satya Murthy Indian Academy of Sciences elected Murthy as a fellow in 1975. The Council of Scientific and Industrial Research awarded him the Shanti Swarup Bhatnagar Prize, one of the highest Indian science awards in 1979. He became an elected fellow of the Indian National Science Academy in 1981. He was also a life member of the Magnetics Society of India. The Indian Physics Association has instituted an annual award, "N. S. Satya Murthy Memorial Award" for recognizing research excellence in physical sciences among young scientists. N. S. Satya Murthy Nivrathi Suryanarayanashastry Satya Murthy (5 February 1936 – 8 October 1984) was