19
Question Question 19
Soni says that the acceleration in an object could be zero even when several forces are acting on it. Do you agree with her? Why?
Acceleration in an object could be zero even when several forces are acting on it. This happens when all the forces cancel out each other i.e., the net force acting on the object is zero.
Consider the below object:
F = ma
F = 0 [∵ equal and opposite forces cancel out each other]
∴ 0 = ma
⇒ a = 0
∴ Vfinal = Vinitial
Hence, if the object was initially moving, it will continue to move with uniform velocity without acceleration.
Therefore, I agree with Soni's statement.
BRIGHT TUTORIALS
BRIGHT TUTORIALS
CBSE Class IX | Academic Year 2026-2027
9403781999
Excellence in Education
Science | Chapter 10: Work and EnergyWeb Content — Quick Reference
Chapter 10: Work and Energy — Quick Reference
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