PrepRung
Sign inSign up free

NDA 2018 GAT · General Knowledge · Work, Energy and Power · easy

A force of 10 N acts on a body and displaces it by 5 m in a direction making an angle of 60 degrees with the force. The work done by the force is

Single correct option

A force of 10 N acts on a body and displaces it by 5 m in a direction making an angle of 60 degrees with the force. The work done by the force is
  1. A. 50 J
  2. B. 25 J
  3. C. 43.3 J
  4. D. 12.5 J
Show answer and solution

Answer: (B) 25 J

Work done is W = F d cos(theta) = 10 × 5 × cos 60° = 10 × 5 × 0.5 = 25 J. Taking 50 J ignores the angle, which is the usual trap. Using sin 60° instead of cos 60° wrongly gives 43.3 J. Only the component of force along the displacement does work.
Report a mistake

Original question written in the NDA 2018 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