Is it possible to measure mass independent of force? And what is mass? Is it material or property? Can a freely falling body satisfy Newton's third law of motion? Such questions generally leave physics students foxed.
There is help available to them now. A book by an expert attempts to answer these questions and many more in simple lucid terms, with worked-out mathematical examples, to clear the haze faced by many students of Class 11 and 12 and those aspiring to take up engineering.
"Beyond the Barriers" by T.V. Krishnan is a compilation of a series of lectures that emphasises on the "simplicity of approach to clarify the concepts".
For example, while elucidating Newton's second law of motion that states "the rate of change of momentum of a body is directly proportional to the applied force and takes place in the direction in which the force acts", the author says that many students are confused with the concept of "pseudo-acceleration" or "fictitious acceleration" used by many authors.
"The terms pseudo-acceleration and fictitious acceleration have caused confusion which could have been eliminated had it been explained that this is nothing but relative acceleration."
Krishnan states rather emphatically that in their attempt to explain and interpret Newton's laws and its implications, many authors tend to "often give less importance" to the original laws compared to their own comments "to such an extent that some textbooks only give their comments on Newton's laws, thereby displacing the laws altogether".
The author, a PhD in physics from the University of Mumbai who was a senior scientist with the Bhabha Atomic Research Centre, says: "Historically it has been observed that an incorrect reading, not faithful to the original text, puts even the scientists on a false scent.
"Every law and theory should be faithfully transmitted as given by the original author. Any interpretation of the laws and personal comments by the authors should be given in such a way that readers can clearly distinguish between the theory and the commentary."
The book, says the author, is "to clear the concepts in physics, classical and modern, and to teach the students how to think for themselves".
In the 35 chapters, Krishnan attempts to answer, with calculations wherever required, questions like: Can one apply Gauss's theorem to a dipole? Is light a particle and a wave or only a particle? Can x-rays travel in a medium faster than light in vacuum?
Krishnan, who did a long stint as professor in an Algerian university, states: "Physics is not difficult. It is exciting. There are no contradictions but only harmony in physics."
Some physical phenomena can be studied by identical mathematical methods though they are very different in a way.
To explain the concept of radioactive decay, he says: "Greater the quantity of water in a tank, greater is the rate of flow of the efflux from a hole. Greater the charge accumulated in a capacitor, faster is the decay. Greater the population in a locality within a uniformly distributed state, greater is the birth rate or death rate."
The author's field of research has been theoretical work in atomic energy levels and x-ray intensities among other topics. He has published several papers in theoretical and experimental physics.
The author-cum-publisher can be reached at email@example.com. The book costs Rs.150.