1. The problem statement, all variables and given/known data From the below information provided, I have to calculate the power which has been transfered to the second pully. 2 pulley system, first pulley has a diameter of 150mm and driven by an electric motor at 250 rev min -1. , second pulley has a diameter of 400mm and is driven by a v-belt, at a load of 200NM. The distance between the two pulleys is 600mm. Included angle of the pulley groove is 40°. Coefficient of friction is 0.4 between belt and pulley. The belt has an ultimate strength of 8kN. 2. Relevant equations Power = Torque x Angluar Velocity 3. The attempt at a solution From one of the other threads I found the below - "Driver speed = 250 revs min-1 = 25pi/3 rad s-1 = 26.18 rad s-1 Driven Speed (angular Velocity) = (25pi/3) * (0.075/0.2) = 25pi/8 rad s-1 = 9.817 rad s-1 Power dissipated at pulley 2 = (25pi/8) * 200 = 625*pi W = 9.817 * 200 = 1963.4 W = 1.9634 kW" I need to understand how the angular velocity has been calculated, as I am unsure where the figures have come from.