The Universe is constantly in motion; nothing is at rest! For our quotidian experience, this reminds us that the only constant is change; but for physics this has interesting technical implications because physicists will often arbitrarily define a system under examination to be "at rest", and thus we see things like references to the "rest-mass" of a particle. My question is: "at rest relative to what?" We have found that the rest-mass of a particle, like the proton, can be defined by the quant

1.5K views · 252 reactions | Question-4 A Man is Walking on a level Road With Velocity 2m/s then Rain Drops appeared to the falling Vertically Down wards With Velocity 2√2 m/s(man see velocity down wards of Rain drops ). Find the Velocity of Rain Observed by man. when man stop walking ? | Mritunjay Lectures | Facebook