CBSE Class 9 Science Question 9 of 21

Work and Energy — Question 12

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Question 12

Can there be displacement of an object in the absence of any force acting on it? Think. Discuss this question with your friends and teacher

Answer

Yes, a uniformly moving object can experience displacement even when no force is acting on it. According to Newton's first law of motion, an object in motion will continue in its straight-line motion unless acted upon by an external force. Therefore, displacement of an object can occur in the absence of any force acting on it.

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Science | Chapter 10: Work and EnergyWeb Content — Quick Reference

Chapter 10: Work and Energy — Quick Reference

work kinetic energy potential energy conservation of energy power kWh

Quick Revision Points

  • Work W = Fs cosθ (joule); W = 0 when F ⊥ s or displacement = 0
  • KE = ½mv²; PE = mgh; Work-energy theorem: W = ΔKE
  • Conservation: energy transforms but total remains constant; PE + KE = constant in free fall
  • Power P = W/t (watt = J/s); 1 HP = 746 W
  • 1 kWh = 3.6 × 10⁶ J = 1 unit of electricity
Exam Tips for Chapter 10
  • Read the detailed chapter notes for complete coverage of all NCERT topics.
  • Practice all NCERT in-text and back exercise questions — they are frequently asked in exams.
  • Focus on comparison tables, diagrams, and definitions — these are high-scoring areas.
  • For numericals (if applicable), practice at least 20 problems of varying difficulty.
  • Refer to the practice question bank (200+ questions) for thorough preparation.
Related Resources
  • Detailed Notes: ch10-work-and-energy.html
  • Practice Questions: 100+ questions with answers in 05-practice-questions/
  • Chapter Test: 30-mark test paper in 06-tests/chapter-tests-30marks/
  • Formula Sheet: Complete formula reference in 03-teacher-aid/formula-sheet.html