31. Is it due to rest mass ? 32. :The rest mass of something traveling at " c " must be zero. 33. In a comoving frame, the dumbbell clearly exerts gravity as fits a 1kg rest mass . 34. This contrasts with a massive particle of which the energy depends on its velocity and rest mass . 35. Likewise, non-material forms of energy can perish into matter, which has rest mass . 36. The quantity of above is ordinary non-relativistic momentum of the particle and its rest mass . 37. Where is the rest mass of the particle and is the speed of light in a vacuum. 38. :: There are two types of particles : those with a rest mass and those without. 39. This was called the " relativistic mass ", and m called the " rest mass ". 40. The ratio of mass of a photon to it's rest mass is infinite for example.
