1. The problem statement, all variables and given/known data So, we have a ring 'A' having mass 'm' that can slide on the horizontal rod. It is attached to a massless string, whose other end is attached to a block of mass 'M = 2m'. 'B' is a massless and frictionless pulley. The problem states that at an instant, the string between ring and the pulley makes an angle 'θ' with the horizontal rod. If the speed of the ring at that instant is 'v', what will be the speed with which the block C descends. 2. Relevant equations Σ Fx = max ∑ Fy = may ∑ Fz = maz 3. The attempt at a solution I have drawn the free body diagrams listing all the forces. The forces acting on the ring 'C' are: Σ Fx = Tcosθ = ma ∑ Fy = N - mg - Tsinθ = 0 Forces acting on the block are: ∑ Fy = T - Mg = Ma' . That's all I did. What I don't understand is, will the acceleration due to the X component of tension force, Tcosθ be the same in magnitude as the acceleration a' of the descending block?