Dynamics - Physics For Class IX (Science Group) - Multiple Choice Questions (MCQs) , Fill in the blanks and Concept Map

Go To Index

Physics For Class IX (Science Group)
UNIT 3: DYNAMICS
Multiple Choice Questions

Section (A) Multiple Choice Questions (MCQs)

Tick mark (✓) the correct answer:
1. Newton's First law of motion is also known as the law of:
(a) speed
(b) rest
(c) Inertia ✓
(d) force

2. Quantity of matter contained in body is called:
(a) mass ✓
(b) volume
(c) area
(d) weight

3. Quantity of motion contained in a body is called:
(a) force
(b) inertia
(c) momentum ✓
(d) gravity

4. Law of conservation of momentum defines that the total momentum of a system of two bodies before and after collision:
(a) remains constant ✓
(b) retains more momentum
(c) losses some momentum
(d) None of the above is true

5. Weigh of a body can be measured using a spring balance, it differs from place to place because of variation in:
(a) acceleration
(b) gravitational pull ✓
(c) velocity
(d) size of spring balance

6. It is easier to push an empty shopping cart than a full one because the filled cart has more mass than the empty one. This can be expressed by:
(a) F > m
(b) F < m
(c) F ∝ 1/m
(d) F ∝ m ✓

7. Centrifugal force is always directed:
(a) towards centre
(b) away from centre ✓
(c) along the circular path
(d) all sides

8. Friction opposes motion between two bodies in contact because of:
(a) charges on bodies
(b) weight of bodies
(c) roughness of surfaces ✓
(d) None of above

9. Which statement is true for limiting frictional force?
(a) It Is greater than rolling friction.
(b) It Is greater than sliding friction.
(c) It Is greater than kinetic friction.
(d) All are true ✓

10. A man pulls a crate of mass 25 kg across the leveled ground with a horizontal force of 60 N. A constant force of friction of 20 N acts on the sledge. What is the acceleration of the sledge?
(a) 0.63 ms^-2
(b) 1.6 ms^-2 ✓
(c) 2.4 ms^-2
(d) 3.2 ms^-2

11. The S.1 unit of force is:
(a) kilogram
(b) Newton ✓
(c) Ampere
(d) Candela

12. The magnitude of a force can be measured using a:
(a) Vernier caliper
(b) screw gauge
(c) light gate
(d) spring balance ✓

13. The momentum depends upon the:
(a) quantity of mass and velocity of the object ✓
(b) quantity of mass and applied force
(c) the velocity of the object and applied force
(d) applied force and acceleration produced

14. Which equation represents the momentum?
(a) ma
(b) m + a
(c) m + v
(d) mv ✓

15. The S.I unit of momentum is:
(a) N
(b) Ns ✓
(c) Ns^-1
(d) Ns^-2

16. Momentum is equal to the:
(a) ma
(b) Fa
(c) Ft ✓
(d) mt

17. It is very useful quantity when it comes to calculate what happens in collision or explosion.
(a) Force
(b) Velocity
(c) Momentum ✓
(d) Torque

18. The property of an object due to which it tends to continue its state of rest or motion is called:
(a) force
(b) inertia ✓
(c) torque
(d) momentum

19. It is resistance to change the state of a body.
(a) Inertia ✓
(b) momentum
(c) torque
(d) acceleration

20. When a bus starts moving the passengers feel a:
(a) sideway jerk
(b) forward jerk
(c) backward jerk ✓
(d) no jerk

21. The acceleration is directly proportional to:
(a) momentum
(b) torque
(c) velocity
(d) force ✓

22. It is inversely proportional to mass of body.
(a) Acceleration ✓
(b) Velocity
(c) Momentum
(d) Torque

23. The force required to move a body along a circular path is called:
(a) gravitational force
(b) centripetal force ✓
(c) centrifugal force
(d) torque

24. The centripetal force is equal to:
(a) mvt
(b) mv/t
(c) mv²t
(d) mv²/t ✓

25. It is the tendency of an object to leave the circular path and fly off in a straight line.
(a) gravitational force
(b) centripetal force
(c) centrifugal force ✓
(d) torque

26. These are always parallel to the plane of contact between two surfaces and opposite to the direction of the applied force:
(a) gravitational forces
(b) centripetal forces
(c) centrifugal forces
(d) frictional forces ✓

27. It is a self-adjusting force.
(a) Friction ✓
(b) Torque
(c) Centripetal force
(d) Centrifugal force

28. It is a force acting on an object at rest that resists its ability to start moving:
(a) Kinetic friction
(b) Sliding friction
(c) Static friction ✓
(d) Rolling friction

29. The maximum static friction is known as:
(a) Kinetic friction
(b) Sliding friction
(c) Static friction
(d) Limiting friction ✓

30. Static friction is greater than:
(a) Kinetic friction ✓
(b) Sliding friction
(c) Rolling friction
(d) Limiting friction

FILL IN THE BLANKS

1. Dynamics is the study of cause of motion.
2. In common force, mass of the object and frictional forces affect the motion of an object.
3. Force is the agent that changes the state of rest or motion of a body.
4. Force can accelerate a body.
5. Momentum is defined as quantity of motion contained in a body.
6. Momentum is product of mass and velocity of a moving object.
7. Newton's first law of motion explains that the objects resist to change their state of rest or motion.
8. Inertia is the property of an object due to which it maintains its state of rest or motion.
9. Newton's second law of motion states that a net force produces acceleration in the direction of force (F= ma).
10. Newton's third law of motion states that for every action, there is an equal and opposite reaction.
11. Centripetal force is required to move a body along a circular path.
12. Centrifugal force is tendency of an object to move away from circular path.
13. Centrifugal force is always opposite and equal to centrifugal force.
14. Centrifuge equipments are helpful in many laboratory as well as daily life processes.
15. The force that resists relative motion between two surfaces is called friction.
16. Maximum static friction is called limiting friction.
17. The static friction is always greater than kinetic friction.
18. The Rolling friction is much lesser than the sliding friction due to smaller contact area.
19. Safety devices are designed to decrease momentum of a body and provide extended time to remain safer.

CONCEPT MAP