An elevator cage of mass carries passengers whose total mass is
PHYSICS · Multi-part · A Level · Physics · Mechanics and materials · Mechanics and materials
Problem
An elevator cage of mass 400kg carries passengers whose total mass is 200kg. The elevator is raised vertically through 20m from rest to rest in 25s at uniform speed by an electric motor. The motor-pulley system is only 80% efficient.
(i) Calculate the useful work done in lifting the loaded elevator.
(ii) Determine the useful power output of the motor during the motion.
(iii) Calculate the electrical power that must be supplied to the motor, taking its efficiency into account.
(iv) If the electricity costs Rs 6.00 per kilowatt-hour, find the cost of a single such lift, leaving your answer to the nearest paise.