A step-type escalator as shown is designed to transport 120 persons per minute at a constant speed v=1.5 ft/s. The overall efficiency of the escalator is estimated to be 70%, and a 200% overload is to be allowed. Assuming that the average weight per person is 160lb, determine the required capacity of the motor of the escalator. The escalator is 15ft high and has a 30 degree angle with the horizon.