Here you not only you can download the PDF with ease rather you can view online in case you are unable to download the PDF or your smartphone doesn’t have a PDF reader.

By the way, I not only uploaded the notes of the 4th chapter, rather of all the chapters of 9th Class Physics have been uploaded here on Top Study World.

Physics is the underlying science for much of technology, and so it is responsible for a large fraction of the wealth of the modern world. If you are reading this essay on a computer screen, that screen would not be possible without a century of physics research.

The computer in which it is displayed would not be possible either. The Internet through which you read this essay also relies on physics discoveries. If physics hadn’t been discovered when it was, some other field might have produced the same results, but we can’t be sure of that.

It’s not just that physics has produced things we like, like computers and medicine and lasers and nuclear power plants. Physics has also produced things we don’t like, like nuclear weapons and pollution from fossil fuels.

But if we had never developed physics, I suspect our lives would be less pleasant than they are now: poorer, shorter, more brutal, and more isolated from one another.

The idea that things fall because they’re attracted to the earth is an ancient one, but it wasn’t until Newton unified all of physics in a single grand design that anyone realized how simple gravity really was.

You might think that’s because Newton was the greatest genius who ever lived. But I wouldn’t be surprised if you think that. After all, Newton said it himself.

He called his theory “the greatest discovery that ever was made by man.” And there’s nothing like the prospect of making a great discovery to make you work hard on something.

But if Newton were alive today, I doubt he’d get funded to study gravity. If you told him you wanted to spend your career working on gravity, he’d think you were crazy.

Previously: KIPS 9th Class Dynamics Physics 3rd Chapter Notes (With PDF)

Do you belong to  Federal Board, Lahore Board, Faisalabad Board, Rawalpindi Board, Sargodha Board, Wah Board? Then these notes are helpful.

How to Download the PDF in PC
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Click to download the pdf of 4th chapter
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Title: Turning Effect of Force

Chapter: 4th Chapter of 9th Class Physics

FileSize: 4 MB

FileType: PDF

Pages: 26

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Short Questions

1. Whal is meant by parallel forces?
2. What is meant by like parallel forces? Also, give examples.
3. What are unlike parallel forces? 
4. Define head to tail rule.
5. Define resolution of vectors. 
6. Define torque or moment of force. · 
7. Define center of mass.
8. Define center of gravity,
9. Define couple and give examples.
10. Define equilibrium.
11. State conditions of equilibrium. 
12. Define stable equilibrium.
13. Define unstable equilibrium
14. Define neutral equilibrium.
15. Define rigid body and axis of rotation.
16. What is meant by the principle of moments?
17. How stability of a body is related to the Position of center of mass?
18. Differentiate between the 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 actio.n 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 the position of its center of gravity?

The Short Questions With Answer In the Below Images

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.
5. What is Centre of Mass? Explain its effect on rotation.
6. What is meant by the center of gravity of a body? Explain· an experiment to find the
centre of gravity of a plate of uniform thickness.
7. Define Couple. Give examples and find torque produced by the couple.
8. What is the equilibrium? State and explain the conditions of equilibrium.
9. Define and explain the three states of equilibrium.
10. How Stability and Position of center of mass are related to each other?
The Above Long Questions With Answers In the Below Images



1. Two equal but unlike parallel forces having a different line of action produces:
2. The number of forces that can be added to head to the tall rule is:
3. The number of perpendicular components of forces are:
4. A force of 10 N is making an angle of 30° with the horizontal. Its horizontal component will be:
5. A couple is formed by:
6. A body is in equilibrium when its:
7. A body is in neutral equilibrium when its center of gravity:
8. Racing cars are made stable by:

Short Questions

1. Define the following:
A) Resultant vector B) Torque C) Center of Mass D) Center of Gravity
2. Differentiate the following.
A) Like and unlike parallel forces
B) Torque and Couple
C) Stable Equilibrium and Neutral Equilibrium
3. How head to tail rule helps to find the resultant of forces?
4. How can a· force be resolved into its rectangular components?
5. When a body is said to be in equilibrium?
6. Explain the first condition for equilibrium.
7. Whey there is need of second condition _for equilibrium if a body satisfied the first condition for equilibrium.
8. What is the second condition of equilibrium?·
9. Give an example of a moving body which is in equilibrium.
10. Think of a body which is at rest but not in equilibrium.
11. When a body cannot be in equilibrium due to a single force on it?
12. Why the height of vehicles is kept as low as possible?
13. Explain what is me􀂍mt by stable, unstable, and neutral equilibrium. Give one example in each case.
MCQs and Short Questions with Answers In the Below Images



1. Find the resultant of the following forces:
(A) 10 N along x-axis
(B). 6 N along y-axis
(C) 4 N along negative x-axis
2. Find the rectangular components of a force of 5O N making an angle of 30° with x -axis.
3. Find the magnitude and direction of a force. If its x – component is 12 N and its y-component is 5 N.

4. A force of 100 N is applied perpendicularly to a scanner at a distance of 10 cm from a

nut. Find torque produced by the force.
5. A force is acting on. A body making an angle of 306 with the horizontal. The horizontal component of force is 20 N. Find the force.
6. The steering of a car has a radius 16 cm. Find the torque produced by a couple of 50 N.
7. A picture frame is hanging by two vertical strings. The tensions in the strings are 3.8
N and 4.4 N. Find the weight of the picture frame.
8. Two blocks of 5 kg and 3 kg are suspended by the two strings are shown. Find the tension in each string.

9. A nut has been tightened by a force of 200 N using 10 cm long spanner. What length of spanned is required to loosen the same nut with 150 N force?

A force is acting on .a body making an angle of 306 with the horizontal. The horizontal component of force is 20 N. Find the force. 

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