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1 - In a belt drive the angle of lap on the small pulley is 150°. With a belt speed of 20m/s and a max tension of 1400N, the greatest power that can be transmitted is 10kW. What power could be transmitted for the same belt speed and max tension if an idler pully is used to increase the angle of lap to 210°. (It may be assumed that centrifugal effects are significant and the mass of the belt is 0.75kg/m)

I know the answer is 12.56kW, but even working backwards is confusing me!

2 - Power is transmitted by a rope drive between two shafts 4.5m apart. The pulleys are 3m and 2m diameter snd the total groove angle is 40°. If the rope has a mass of 4 kg/m, and the max tension is 20kN, determine the max power which the rope can transmit, and the corresponding speed of the smaller pulley. Coefficient of friction is 0.2.

Again .. the answers are 446kW and 390 rev/min