These Class 9 Physics Chapter 4 constructive questions are ExamPaperDesk’s own solved answers to the constructed response questions of Chapter 4, Turning Effect of Forces, in English medium and Urdu medium. Constructed response questions are the part of the paper where students lose the most marks, because a correct final answer earns little without the reasoning. Every answer here shows the formula, the substitution and the conclusion in the order an examiner expects.
What Chapter 4 Covers
- Turning effect of forces, torque and the moment of a force
- Centre of mass and centre of gravity, and the conditions for stability
- Equilibrium and the two conditions a body must satisfy to stay in equilibrium
- Circular motion and centripetal force, including Fᶄ = mv² / r
- Everyday applications, from banked roads to balancing objects
What You Get in These Answers
The PDFs work through the constructed response questions of the chapter exercise, one by one. For example, the first question asks which of two curves of different radius makes a car experience more centripetal force. The answer does not simply say “the smaller one” — it starts from Fᶄ = mv² / r, points out that mass and speed are unchanged, deduces that Fᶄ is inversely proportional to r, and finishes with the ratio F₁ / F₂ = r₂ / r₁ to prove the result. That is the structure you need in the exam.
How to Use These Answers
Attempt each question on your own paper before you look. When you compare, check three things: did you state the correct relation, did you justify why the other quantities stay constant, and did you finish with a clear conclusion? Marks in this section are given for the steps, not just the last line.
Chapter 4 Constructive Questions — English Medium PDF
Chapter 4 Constructive Questions — Urdu Medium PDF
Related Class 9 Physics Resources
Practise the rest of the chapter with the Chapter 4 exercise short questions, and browse all Class 9 Physics exercise short questions and constructive questions. The Class 9 Physics section collects notes, test papers, online papers, guess papers and past papers chapter by chapter.
Chapter 4 Constructive Questions: Turning Effects of Force
The constructive questions at the end of Chapter 4 describe a situation and ask you to account for it. They are the closest thing in the textbook to the nine-mark questions in the annual paper. In this chapter they deal with:
- Why a longer spanner loosens a nut more easily.
- How the principle of moments explains a see-saw and a shopkeeper balance with unequal arms.
- Why a wide base and a low centre of gravity make a vehicle stable.
- What provides the centripetal force in various cases, and what happens when it is removed.
What a Full-Mark Answer Looks Like Here
These answers are marked point by point, so an answer that circles the idea without stating it plainly scores badly. For Turning Effects of Force in particular:
- Say perpendicular distance, not just distance, every time torque appears.
- For stability, argue from where the vertical line through the centre of gravity falls relative to the base.
- Name the law or principle first, then apply it to the objects actually named in the question.
- Draw and label a diagram wherever one is possible, since it often carries a mark by itself.
Why This Set Repays the Effort
Most students drill the short questions and leave the constructive ones until last, which is the wrong way round. Eighteen of the sixty marks in the annual paper come from long questions built on exactly this material, and a reasoning question cannot be answered from memory alone. Attempt them in writing with the book closed, then compare.
Frequently Asked Questions
Why is a vehicle with a wide base and low centre of gravity more stable?
Because the vertical line through its centre of gravity stays inside the base over a larger tilt, so the weight produces a restoring moment instead of toppling it.
How many marks do the long questions carry?
Eighteen of the sixty. Three are offered and you attempt any two, at nine marks each, split into a four-mark and a five-mark part.
Related Class 9 Physics Resources
For the two-mark recall answers from the same chapter see the Chapter 4 exercise short questions, and check your understanding with the Chapter 4 online test. Continue with Chapter 3 and Chapter 5, or download the 25 Class 9 Physics guess papers for timed practice. Browse Class 9 Physics notes for the rest.
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