The motor M is connected to the speed reducer C by the tubular shaft and coupling. The sha...

The motor M is connected to the speed reducer C by the tubular shaft and coupling. The shaft has an outer and inner diameter of 1 in. and 0.75 in., respectively, and is made from a material having an allowable shear stress of Tallow = 12 ksi, when the motor supplies 20 hp of power. Determine the smallest allowable angular velocity of the shaft.