# Class 9 Science MCQ Chapter 9 Force and Laws of Motion

Class 9 Science MCQ Chapter 9 Force and Laws of Motion, Class 9 Science MCQ Question Answer, Class 9 Science Multiple Choice Question Answer to each chapter is provided in the list of SCERT Science Class 9 Objective Types Question Answer so that you can easily browse through different chapters and select needs one. Class 9 Science MCQ Chapter 9 Force and Laws of Motion Question Answer can be of great value to excel in the examination.

## SCERT Class 9 Science MCQ Chapter 9 Force and Laws of Motion

SCERT Class 9 Science MCQ Chapter 9 Force and Laws of Motion Notes covers all the exercise questions in SCERT Science Textbooks. The NCERT Class 9 Science MCQ Chapter 9 Force and Laws of Motion provided here ensures a smooth and easy understanding of all the concepts. Understand the concepts behind every chapter and score well in the board exams.

Force and Laws of Motion

Chapter – 9

### Multiple Choice Questions & Answers

1. An object gains motion by –

(a) gravitation

(b) momentum

(c) balanced force

(d) unbalanced force

Ans: (d) unbalanced force.

2. A fan is moving on. Switch off the fan but the fan is moving continue for sometimes, what is the reason?

(a) momentum

(b) unbalanced force

(c) inertia

(d) balanced force

Ans: (c) inertia.

3. Amoving car is braked suddenly, the passengers bend infrared. What is the reason –

(a) inertia

(b) for momentum conservation

(c) momentum

(d) unbalanced force

Ans: (a) inertia.

4. Two force acting on a wooden block. But the block has no moved. Then the force is –

(a) unbalanced force

(b) balanced force

(c) force is equal to zero

(d) for inertia

Ans: (b) balanced force.

5. All planets must orbit the sun. It was firstly provided by –

(a) Newton

(b) Kepler

(c) Galileo Galili

(d) copernicus

Ans: (c) Galileo Galili.

6. From observation of Galileo Galili, four small bodies orbiting –

(a) Jupiter

(b) earth

(c) moon

(d) sun

Ans: (a) Jupiter.

7. Safety belts are worn to prevent –

(a) collision

(b) speed

(c) save driver

(d) accident

Ans: (d) accident.

8. An object is the mass of 10 kilogram. The inertia of the object is –

(a) 20kg

(b) 10kg

(c) 5kg

(d) 15kg

Ans: (b) 10kg.

9. An objects is mass of 10kg. It moves with 10ms¹ velocity. Then the momentum is –

(a) 100 mkg⁻¹

(b) 20kgms⁻¹

(c) Okgms⁻¹

(d) Imkg⁻¹

Ans: (a) 100 mkg⁻¹

10. An object is mass of 10kg. It moves with 10ms⁻² accelerated. Then the force is –

(a) 100 Newton

(b) 20 Newton

(c) 0 Newton

(d) 1 Newton

Ans: (a) 100 Newton.

11. What is the S. I. unit of momentum?

(a) Kgms⁻²

(b) Kgms⁻¹

(c) Kgms

(d) Kgms²

Ans: (b) Kgms-¹.

12. What is the value of In?

(a) 1kg * 1 ns⁻¹

(b) 1kg x 1ms⁻²

(c) 1kg x 1 n X

(d) 1kg × 1m⁻¹

Ans: (b) 1kgx1ms-²

13. One of the law of motion is called law of inertia. Which is it?

(a) 1st law of motion

(b) 2nd law of motion

(c) 3rd law of motion

(d) All of the above

Ans: (a) 1st law of motion.

14. As the Sailor jumps is forward direction the boat moves backward. It is the example of Newton, s

(a) 1st law of motion

(b) 2nd law motion

(c) third law motion

(d) inertia

Ans: (c) third law motion.

15. If (mAuA + mB + uB) is the total momentum of the two balls A and B at before the collision and (mAvA + mBvB) is the total momentum after the cellusion.

Then which is correct in the following.

(a) mAuB = mAvA X mBvB

(b) mAuA-mBuB = mAvA-mBvB

mAuA          mAvA

(c)  ———— = ————

mBuB.          mBvB

(d) mAuA + mBmB = mAvA + mBvB

Ans: (d) mAuA + mBmB = mAvA + mBvB .

16. If (mAuA + mBuB) and (mAvA + mBvB) are the total momentum before the collision and after the collision respectively of the two ball A and B. Then mAuA + mBuB = mAvA+mBvB. It is called –

(a) Newton’s 2nd law of motion

(b) the law of conservation of momentum

(c) momentum

(d) momentum

Ans (b) the law of conservation of momentum.

17. If force F, mass m and acceleration a, then Newton’s 2nd law’s mathematical representation is-

(a) F = m + a

m

(b) F = ——–

a

(c) F = ma

(d) F = m-a

Ans: (c) F = ma.

#### Very Short Answer Type Questions

1. What do you mean by balanced forces?

Ans: A matter is pulled from both the sides with equal forces, the block will not move. Such forces are called balanced forces.

2. What do you mean by unbalanced force?

Ans: A matter is pulled from both or one side unequal forces, the block will move. Such forces are called unbalanced force.

3. When does a matter gain to move?

Ans: When the unbalanced force acts the matter.

4. State the first law of motion.

Ans: An object remains is a state of rest or of uniform motion is a straight line unless compelled to change that by an applied force.

5. What is called inertia?

Ans: The tendency of undisturbed objects to stay at rest or to keep moving with the the some velocity is called inertia.

6. Give an example of rest inertia.

Ans: When we are standing is a bus and the bus begins to move suddenly. We tend to fall back ward.

7. Give an example of moving inertia?

Ans: A moving car, if it breaks suddenly, the passengers body goes forward same direction.

8. Who invented pendulum clock?

Ans: Galileo-galice.

9. What is the measure of inertia?

Ans: The mass of an object is a measure of its inertia.

10. Whose inertia is more between train and cart?

Ans: The inertia of train is more. Because the train has more mass than cart. momentum?

11. What is called momentum?

Ans: The product of mass and velocity is called momentum.

12. Write the mathematical expression of momentum.

Ans: Momentum p, the mass m, and velocity v, the p = mv

13. Write S. I. unit of momentum?

Ans: Kilogram-metre per second (kgms⁻¹)

14. State the 2ⁿᵈ law of motion.

Ans: The rate of change of momentum of an object is proportional to the applied unbalanced force is the direction of force.

15. Write the mathematical expression of 2ⁿᵈ law of motion.

Ans: Force F, mass m and acceleration at the according to.2nd law of motion is F = ma.

16. What is the S. I. unit of force?

Ans: Newton or Kg Ms⁻²

17. What is the symbol of Newton?

Ans: N.

18. When is the equal value of initial velocity and final velocity?

Ans: When

Force, F = 0.

19. Find the force, when 2 kg mass moving with at 5ms⁻² accelerating?

Ans: F: = ma

= 2 × 5ma²

10 Newton.

20. Find the force, when 4 kg mass moving with at 2ms-² accelerating?

Ans: F = ma

= 4kg x 2ms⁻²

= 8 Newton.

21. State the third law of motion?

Ans: To every action there is an equal and opposite direction.

22. Give an example of third law of motion.

Ans: As the sailor jumps is forward direction the boat moves ard.

23. Write the law of conservation of momentum.

Ans: The sum of momenta of th two objects before collision is equal to the sum of momenta after the collision provided there is no external unbalanced force acting them.

24. An object mass of m, moves with velocity v.What is the momentum.

Ans : mv.

25. An object mass of 2 kg moves with velocity 5ms⁻¹ What is the momentum of the object?

Ans: P = mv

= 2 × 5ms⁻¹

= 10 kgms⁻¹

26. What do you mean by momenta?

Ans: Momenta is the plural form of momentum.

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