Gce Model Questions Vol1 2018 Physics Question 43

Practice objective / multiple choice question 43 from the 2018 Gce Model Questions Vol1 Physics examination.

Gce Model Questions Vol1 2018 Physics Objective / Multiple Choice Medium Difficulty
Question 43 GCE_MODEL_QUESTIONS_VOL1 • 2018 • PHYSICS • objective

An electric motor is rated at 1500 W electrical input and operates at a speed of 3000 rpm with an efficiency of 80 % at this speed. The motor drives a load through a gearbox with a speed reduction ratio of 4 : 1 (motor turns four times for each load turn) and a mechanical efficiency of 90 %. The load requires a torque of 10 N·m at 750 rpm. (i) Can the motor supply the required torque? (ii) Assuming the motor can meet the load demand, calculate the overall efficiency of the system (ratio of useful mechanical power delivered to the load to the electrical power drawn by the motor).

Answer Options

Correct Answer A. Yes, the motor can supply the torque; overall efficiency ≈ 52 %
B. Yes, the motor can supply the torque; overall efficiency ≈ 60 %
C. No, the motor cannot supply the torque; overall efficiency ≈ 55 %
D. No, the motor cannot supply the torque; overall efficiency ≈ 48 %
Correct Answer
A
Correct Option:
Yes, the motor can supply the torque; overall efficiency ≈ 52 %

About This Question

This is Gce Model Questions Vol1 2018 Physics Question 43. It is one of the objective questions from the 2018 Gce Model Questions Vol1 Physics examination.

Difficulty level: Medium .

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