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NDA 2017 GAT · General Knowledge · Work, Energy and Power · medium

A motor lifts a load of 100 kg through a height of 10 m in 10 s. Taking g = 10 m/s^2, the power delivered to the load is

Single correct option

A motor lifts a load of 100 kg through a height of 10 m in 10 s. Taking g = 10 m/s^2, the power delivered to the load is
  1. A. 100 W
  2. B. 1000 W
  3. C. 10000 W
  4. D. 10 W
Show answer and solution

Answer: (B) 1000 W

The work done equals the gain in potential energy, mgh = 100 x 10 x 10 = 10000 J. Power is work divided by time, so P = 10000/10 = 1000 W. Omitting the time gives 10000, and dividing the mass by the time wrongly gives 10. This also equals 1 kW, which is about 1.34 horse power.
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Original question written in the NDA 2017 GAT pattern and checked twice for the correct answer. Not an official question paper. How we write and check questions · Corrections policy · Report a mistake