5.16 An elevator cable suspends an el- evator car and passengers with a total mass of 550 kg in the Omnicorp regional headquarters. If the car is being raised at a constant speed of 1.2 ms-l then: (a) At what rate is work being done by the cable on the car? The efficiency of the motor at converting electrical power to mechanical power is just 15% (b) How much electrical power is being used to raise the car? Budgets are being slashed at Omnicorp and the amount of power used by eleva- tors has to be reduced by 10%. (c) At what speed are the elevators raised under the new regime? An engineer discovers a way to use the elevator motor to actually generate elec- tricity when lowering the elevator car. If the efficiency of this process is just 5% then: (d) How much electricity is generated when lowering the car 55 m from the top floor to the ground floor? How much electrical energy is used (e) up when raising the elevator from the ground floor to the top floor?

5.16 An elevator cable suspends an el- evator car and passengers with a total mass of 550 kg in the Omnicorp regional headquarters. If the car is being raised at a constant speed of 1.2 ms-l then: (a) At what rate is work being done by the cable on the car? The efficiency of the motor at converting electrical power to mechanical power is just 15% (b) How much electrical power is being used to raise the car? Budgets are being slashed at Omnicorp and the amount of power used by eleva- tors has to be reduced by 10%. (c) At what speed are the elevators raised under the new regime? An engineer discovers a way to use the elevator motor to actually generate elec- tricity when lowering the elevator car. If the efficiency of this process is just 5% then: (d) How much electricity is generated when lowering the car 55 m from the top floor to the ground floor? How much electrical energy is used (e) up when raising the elevator from the ground floor to the top floor?