Asquare thread power screw is designed to provide 150n of lifting force at a rate of 15mm/s. the power screw is driven directly by a motor. the screw has a nominal diameter of 12mm and a pitch of 3mm. the screw-nut combination has a coefficient of friction of 0.06 and there is a 30mm diameter collar with a coefficient of friction of 0.08. a. determine the total torque required to lift the load as described b. determine the required power of the motor c. determine the factor of safety for torsion failure at the root diameter