7.1.1 When is work done equal to zero?

Last updated at June 30, 2026 by

šŸ’¬ Tired but no work?

Push hard against a wall that does not move. You feel exhausted — yet in the scientific sense you may have done no work at all. How?

When is the work done by a force zero?
  • If the force is zero (\(F = 0\)), no work is done.
  • If there is no displacement (\(s = 0\)), no work is done — e.g. pushing a rigid wall. You feel tired because your muscles use internal energy, but no work is done on the wall.
  • If the force is perpendicular to the displacement , the work done by that force is zero (there is no displacement in the direction of the force).
šŸ”¹ Ready to Go Beyond
  • When a girl carries a box while walking, she pushes up to balance its weight while the box moves horizontally. Force and displacement are perpendicular, so this force does no work on the box.
  • In higher grades you will learn how to find the work done when force and displacement are at an angle to each other.
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CA Maninder Singh is a Chartered Accountant with 16+ years of practical experience and 20+ years of teaching experience. At Teachoo, he simplifies Accounts, Tax and GST with step-by-step examples so students can apply concepts confidently in exams and real life.

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