1. The problem statement, all variables and given/known data Please refer diagram attached. The pulleys are moving down with constant speed u each. Pulleys are light , string ideal. What is the speed with the mass moves up? 2. Relevant equations 3. The attempt at a solution Now, I got the answer as ucosΘ, obviously. But the answer is u/cosΘ. the solution too is given. But I feel that the latter is wrong as the velocity goes to to infinity as the mass goes upwards. Please tell me which is correct.