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NDA 2020 GAT · General Knowledge · Work, Energy and Power · medium

A force of 50 N acts on a body at an angle of 60 degrees to the horizontal and moves it through 4 m horizontally. The work done by the force is

Single correct option

A force of 50 N acts on a body at an angle of 60 degrees to the horizontal and moves it through 4 m horizontally. The work done by the force is
  1. A. 200 J
  2. B. 173 J
  3. C. 100 J
  4. D. 25 J
Show answer and solution

Answer: (C) 100 J

Work W = F d cos(theta) = 50 x 4 x cos 60 = 50 x 4 x 0.5 = 100 J. The answer 200 J ignores the angle, and 173 J results from using sin 60 in place of cos 60. Only the component along the displacement does work.
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Original question written in the NDA 2020 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