Relativistic Momentum Which one of the following statements about linear momentu
ID: 2018531 • Letter: R
Question
Relativistic Momentum Which one of the following statements about linear momentum is true (p = magnitude of the momentum, m = mass, and v = speed)?When the magnitude p of the momentum is defined as p = mv/ , the linear momentum of an isolated system is conserved only if the speeds of the various parts of the system are very high. When the magnitude p of the momentum is defined as p = mv, the linear momentum of an isolated (system is conserved only if the speeds of the various parts of the system are very high. When the magnitude p of the momentum is defined as p = mv/ , the linear momentum of an isolated system is conserved no matter what the speeds of the various parts of the system are. When the magnitude p of the momentum is defined as p = mv, the linear momentum of an isolated system is conserved no matter what the speeds of the various parts of the system are.Explanation / Answer
Recall that special relativity is built on two postulates: 1) the speed of light is the same in all inertial reference frames, and 2) the laws of physics are the same in all inertial reference frames. So, if momentum is conserved at slow speeds, it will also be conserved at high speeds. Rule out choices a) and b). Now, choice d) does not include relativistic speeds, as you know the formula for relativistic momentum takes over at high speeds. So, the correct answer is c), because the formula for relativistic momentum reduces to that of non-relativistic momentum at slow speeds.