# Chapter 4 – Turning Effect of Forces

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## Contents

Section 2:  (Exercise: Numericals)

Section 3:  (Extra: MCQ’s)

Section 4:  (Extra: Short Questions)

1. What is meant by parallel forces?
2. What is meant by like parallel forces? Also give examples. (LHR 2011, 2014, 2015, GRW 2013)
3. What are unlike parallel forces?          (LHR 2011, 2014, 2015 GRW 2013)
4. Define head to tail rule. (GRW 2015)
5. Resultant Force        (LHR 2011, 2013, GRW 2013)
6. Define resolution of vectors.      (LHR 2012, GRW 2014, 2015)
7. Define torque or moment of force.      (GRW 2012, LHR 2012, 2013)
8. Define centre of mass.    (LHR 2014, 2015)
9. Define centre of gravity.          (LHR 2012, 2013, 2014 GRW 2015)
10. Define couple and give examples.
11. Define equilibrium.
12. State conditions of equilibrium.
13. Define stable equilibrium. (GRW 2015)
14. Define unstable equilibrium. (GRW 2014)
15. Define neutral equilibrium.
16. Define rigid body and axis of rotation.       (LHR 2012, 2014, GRW 2015)
17. What is meant by principle of moments?   (GRW 2013, 2014)
18. Differentiate between axis of rotation and point of rotation?
19. On what factors rotation produce in a body depend?
20. How can we increase torque by keeping the force constant?
21. Can a moving body be in equilibrium? Explain.
22. Will a body be in equilibrium under the action of a single force?
23. Can a body be in equilibrium if it is revolving clockwise under the action of a single force?
24. Give an example of a case when the resultant force is zero but resultant torque is not zero.
25. How do we know whether a body is in a stable or unstable equilibrium due to position of its centre of gravity?

Section 5:  (Extra: Long Questions)

1. Which method is used for addition of forces? Explain with example.
2. Resolve the vector into its rectangular components.
3. Find the magnitude and direction of a vector whose rectangular components are given.
4. Explain torque or moment of a force.     (GRW 2011, LHR 2012)
5. What is Centre of Mass? Explain its effect on rotation.
6. What is meant by centre of gravity of a body? Explain an experiment to find the centre of gravity of a plate of uniform thickness.       (GRW 2014, LHR 2014)
7. Define Couple. Give examples and find torque produced by couple.
8. What is equilibrium? State and explain the conditions of equilibrium.
9. Define and explain the three states of equilibrium.
10. How Stability and Position of centre of mass are related to each other?