Answer to Question #162843 in Mechanics | Relativity for Benjamin

Question

Consider the statement: If an object is moving, then its change in momentum is non-zero. (a) Is this statement valid? __________ (b) If you contend the statement is valid, how do you know? (c) If you contend the statement is invalid, what is wrong with it? (d) If the statement is invalid, restate it to give a valid statement. 

Answer 1

If object is moving then it will have some non zero velocity. Since momentum is the product of velocity and mass, so it is non zero. For the given statement, if object is moving with uniform velocity then change in momentum is zero. So given statement is not valid for all times.

If object is moving with variable velocity then it has non zero change in momentum.