A high-speed elevator is being designed that must be able to travel at a maximum

Question

A high-speed elevator is being designed that must be able to travel at a maximum speed of 11.5 fts. You are asked to recommend the lift motor to use. The completely furnished carriage will have a mass of 3500 pounds. The design occupancy limit will be eight people weighing an average of 200 pounds. Since there will always be some unknowns in the actual operation of the elevator, use a Factor of Safety of 2. In other words, recommend a motor that has exactly twice the power rating needed (based on all the design limit specifications). How big of a motor, in hp, should you you recommend?

Explanation / Answer

v = 11.5 ft/s   = 11.5 x 0.3048 = 3.51 m/s

M = (3500 + 200) x 0.454 = 1679.8 kg

F = Mg = 16462.04 N

P = F.v = 57781.76 Watt

considering security factor

power reqauired = 2 x 57781.76 watt = 2 x 57781.76 x 0.001341hp = 154.97 hp

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