📘 Chapter 4: Turning Effect of Forces – Multiple Choice Questions
Prepared by Muhammad Tayyab, Subject Specialist Physics, Govt Christian High School Daska. Based on PECTAA 2026 syllabus (National Curriculum 2023).
📖 What's Inside: This section covers multiple choice questions from Chapter 4 Turning Effect of Forces including resultant of forces, rectangular components, torque, equilibrium, principle of moments, stability, centre of mass, and centripetal force. Each question is presented with an interactive quiz format and a detailed answer key with explanations as per the official PECTAA 2026 Physics curriculum. Perfect for Punjab Boards (Lahore, Gujranwala, Multan, etc.) and all BISE boards across Pakistan.
📚 Related Resources – Chapter 4: Turning Effect of Forces
📋 Exercise Short Qs
📝 Short Qs
📖 Comprehensive Qs
🔢 Numerical Problems
✅ MCQs
✏️ Constructed Response
Turning Effect of Forces covers torque, equilibrium, center of mass, and couple.
🧪 Interactive MCQs (PECTAA 2026)
Select the best answer for each question. Click "Check Answer" to see if you're correct and read the explanation. Use "Reset" to try again.
4.1
A particle is simultaneously acted upon by two forces of 4 and 3 newtons. The net force on the particle is:
✅ Correct Answer: (B) between 1 N and 7 N
The resultant of two forces can range from the difference to the sum of their magnitudes (4 – 3 = 1 N to 4 + 3 = 7 N).
The resultant of two forces can range from the difference to the sum of their magnitudes (4 – 3 = 1 N to 4 + 3 = 7 N).
4.2
A force \(F\) is making an angle of 60° with x-axis. Its y-component is equal to:
✅ Correct Answer: (B) \(F \sin 60^\circ\)
The y-component of a force is given by \(F_y = F \sin \theta\). Therefore, \(F_y = F \sin 60^\circ\).
The y-component of a force is given by \(F_y = F \sin \theta\). Therefore, \(F_y = F \sin 60^\circ\).
4.3
Moment of force is called:
✅ Correct Answer: (D) torque
The moment of a force is also called torque. It is the product of force and the perpendicular distance from the axis of rotation.
The moment of a force is also called torque. It is the product of force and the perpendicular distance from the axis of rotation.
4.4
If \(F_1\) and \(F_2\) are the forces acting on a body and \(\tau\) is the torque produced in it, the body will be completely in equilibrium, when:
✅ Correct Answer: (A) \(\sum F = 0\) and \(\sum \tau = 0\)
For complete equilibrium, both the first condition (translational) and the second condition (rotational) must be satisfied.
For complete equilibrium, both the first condition (translational) and the second condition (rotational) must be satisfied.
4.5
A shopkeeper sells his articles by a balance having unequal arms of the pans. If he puts the weights in the pan having shorter arm, then the customer:
✅ Correct Answer: (A) loses
With a balance having unequal arms, putting weights in the pan with the shorter arm means the customer receives less actual weight than what is shown.
With a balance having unequal arms, putting weights in the pan with the shorter arm means the customer receives less actual weight than what is shown.
4.6
A man walks on a tight rope. He balances himself by holding a bamboo stick horizontally. It is an application of:
✅ Correct Answer: (C) principle of moments
The bamboo stick helps the tightrope walker maintain balance by adjusting the centre of gravity, which is an application of the principle of moments.
The bamboo stick helps the tightrope walker maintain balance by adjusting the centre of gravity, which is an application of the principle of moments.
4.7
In stable equilibrium, the centre of gravity of the body lies:
✅ Correct Answer: (B) at the lowest position
In stable equilibrium, the centre of gravity is at its lowest possible position, making the body tend to return to its original position after being tilted.
In stable equilibrium, the centre of gravity is at its lowest possible position, making the body tend to return to its original position after being tilted.
4.8
The centre of mass of a body:
✅ Correct Answer: (D) may lie within, outside or on the surface
The centre of mass can be inside, outside, or on the surface of a body depending on its shape (e.g., a ring's centre of mass is outside the material).
The centre of mass can be inside, outside, or on the surface of a body depending on its shape (e.g., a ring's centre of mass is outside the material).
4.9
A cylinder resting on its circular base is in:
✅ Correct Answer: (A) stable equilibrium
A cylinder on its circular base returns to its original position when tilted, so it is in stable equilibrium.
A cylinder on its circular base returns to its original position when tilted, so it is in stable equilibrium.
4.10
Centripetal force is given by:
✅ Correct Answer: (C) \(\frac{mv^2}{r}\)
The centripetal force formula is \(F_c = \frac{mv^2}{r}\), where \(m\) is mass, \(v\) is speed, and \(r\) is the radius of the circular path.
The centripetal force formula is \(F_c = \frac{mv^2}{r}\), where \(m\) is mass, \(v\) is speed, and \(r\) is the radius of the circular path.
📋 Answer Key with Explanations
| Q. No | Correct Answer | Explanation |
|---|---|---|
| 4.1 | (B) between 1 N and 7 N | The resultant of two forces can range from difference to sum (4 – 3 to 4 + 3 = 1 to 7 N). |
| 4.2 | (B) \(F \sin 60^\circ\) | y-component = \(F \sin \theta\), so y-component = \(F \sin 60^\circ\). |
| 4.3 | (D) torque | Moment of force is also called torque. |
| 4.4 | (A) \(\sum F = 0\) and \(\sum \tau = 0\) | For complete equilibrium, both first and second conditions must be satisfied. |
| 4.5 | (A) loses | If the weight pan has a shorter arm, the customer receives less actual weight than shown. |
| 4.6 | (C) principle of moments | The bamboo stick helps maintain balance by adjusting the centre of gravity. |
| 4.7 | (B) at the lowest position | In stable equilibrium, the centre of gravity is at its lowest possible position. |
| 4.8 | (D) may lie within, outside or on the surface | Centre of mass can be inside, outside, or on the surface of a body. |
| 4.9 | (A) stable equilibrium | A cylinder on its circular base returns to original position when tilted. |
| 4.10 | (C) \(\frac{mv^2}{r}\) | Centripetal force formula is \(F_c = \frac{mv^2}{r}\). |
💡 Exam Tip:
For MCQs, focus on understanding the core concepts rather than memorizing facts. Pay attention to key definitions like torque, equilibrium conditions, and the principle of moments. Practice with these interactive questions to test your knowledge and identify areas that need more revision. These MCQs follow the PECTAA 2026 pattern and are prepared by Subject Specialist Muhammad Tayyab.
Chapter 1Physical Quantities and Measurements
Chapter 2Kinematics
Chapter 3Dynamics
Chapter 4✨ Turning Effect of Forces
Chapter 5Work and Energy
Chapter 6Mechanical Properties of Matter
Chapter 7Thermal Properties of Matter
Chapter 8Magnetism
Chapter 9Nature of Science
📖 Complete syllabus coverage for Class 9 Physics (PECTAA 2026) – Chapters 1 to 9
Created by Hira Science Academy | Aligned with PECTAA 2026 Syllabus