1. The problem statement, all variables and given/known data Sand falls at a rate of 0.5 kg/s onto a conveyor belt which is moving at a constant speed of 2.0 m/s. Questions: a. Find the power expended in driving the belt! b. Find the rate at which the sand acquires kinetic energy! c. Account for any difference between the answer in part (a) and (b) 2. Relevant equations F = m.(dv/dt) + v (dm/dt) P = W/t = F.v 3. The attempt at a solution For question (a), i think: P = F.v = [m.(dv/dt) + v (dm/dt)].v ; dv/dt = 0 = (dm/dt) . v^2 = ..... W Is it right ? For question (b) i have no idea about the question. The question asked about speed or Power ? Thanks a lot.