1. The problem statement, all variables and given/known data For impulse momentum, I know that collision between two object, impulse = 0. Can somebody explain to me how come for this question the impulse is 0 "shaft A engaged to shaft b" has the same meaning as collision? And I assume that it is right for me to add shaft A and shaft b moment of inertia together in order to solve the question but can somebody explain the reason behind it? Thanks alot.