| Subject | Science |
| Chapter 8 | Force and Laws of Motion |
| Questions Type | Multiple Choice Questions (MCQs) |
| File Download |
Class 9 Science Force and Laws of Motion MCQ
1. An external influence which changes or tends to change the state of rest or uniform motion of body or its dimensions is called:
(A) momentum
(B) force
(C) moment of force
(D) pressure
Correct Answer: (B)
2. Equal and opposite forces acting on a body which do not change its state of rest or uniform motion are called:
(A) like parallel forces
(B) unlike parallel forces
(C) balanced forces
(D) all the above
Correct Answer: (C)
3. The unequal and opposite forces acting on a body, which change its state of rest or uniform motion are called:
(A) unbalanced forces
(B) unlike parallel forces
(C) like parallel forces
(D) all the above
Correct Answer: (A)
4. Force of friction always acts in the direction:
(A) of applied force
(B) opposite to the direction of applied force
(C) at right angles to the direction of applied force
(D) none of the above
Correct Answer: (B)
5. When balanced forces act on a body, the body:
(A) must remain in its state of rest
(B) must continue moving with uniform velocity, if already in motion
(C) must experience some acceleration
(D) both (A) and (B)
Correct Answer: (D)
6. When unbalanced forces act on a body, the body:
(A) must move with uniform velocity
(B) must remain at rest
(C) must experience acceleration
(D) must move in a curved path
Correct Answer: (C)
7. If no external force acts on a body, it will:
(A) move with more speed
(B) change its shape
(C) break into pieces
(D) either remain in its state of rest or in uniform motion.
Correct Answer: (D)
8. If a body is allowed it freely fall from a height, its speed increases continuously. It is because:
(A) air does not exert frictional force
(B) magnetic force of the earth increases its speed
(C) the gravitational force of the earth increases its speed
(D) pressure of air forces it downward
Correct Answer: (C)
9. When a running motorbike accelerates suddenly, the pillion rider has a tendency to fall backward. This is an example of the:
(A) Newton’s first law of motion
(B) Newton’s second law of motion
(C) Newton’s third law of motion
(D) Newton’s law of gravitation of motion
Correct Answer: (A)
10. The tendency of a body to continue in its state of rest or uniform motion, even on the application of external force is called:
(A) force
(B) momentum
(C) inertia
(D) impulse
Correct Answer: (C)
11. The inertia of an object tends to cause the object
(A) to increase its speed
(B) to decrease its speed
(C) to resist any change in its state of motion
(D) to decelerate due to friction
Correct Answer: (C)
12. An object of mass 2 kg is sliding with a constant velocity of 4 ms–1 on frictionless horizontal table. The force required to keep the object moving with the same velocity is
(A) 32 N
(B) 0 N
(C) 2 N
(D) 8 N
Correct Answer: (B)
13. A water tanker filled up to 2/3 of its height is moving with a uniform speed. On a sudden application of brakes, the water in the tank would
(A) move backward
(B) move forward
(C) be unaffected
(D) rise upwards
Correct Answer: (B)
14. When a car at high speed makes a sharp turn, the driver in a car tends to get thrown to the side opposite to the turn. This is due to
(A) inertia of motion
(B) inertia of time
(C) inertia of rest
(D) inertia of direction
Correct Answer: (D)
15. Which of the following is an incorrect statement?
(A) Mass is measure of inertia of a body.
(B) Newton’s first law of motion is the law of inertia.
(C) Unbalanced force produced constant velocity.
(D) None of these
Correct Answer: (C)
16. Inertia is the property of a body by virtue of which, it cannot change by itself
(A) its state of rest
(B) its steady state of uniform motion
(C) its direction motion
(D) all of these
Correct Answer: (D)
17. An athlete does not come to rest immediately after crossing the winning line due to the
(A) inertia of motion
(B) inertia of rest
(C) inertia of direction
(D) none of these
Correct Answer: (A)
18. Question which of the following has largest inertia?
(A) A pin
(B) An inkpot
(C) Your physics book
(D) Your body
Correct Answer: (D)
19. The SI unit of momentum is:
(A) newton
(B) newton-second
(C) dyne
(D) dyne-second
Correct Answer: (B)
20. Momentum is a:
(A) vector quantity
(B) scalar quantity
(C) fundamental quantity
(D) None of these
Correct Answer: (A)
21. The magnitude of a physical quantity is 8.5 Ns. The physical quantity is:
(A) force
(B) momentum
(C) pressure
(D) moment of force
Correct Answer: (B)
22. Which is the correct statement? A spaceship continues moving in space with uniform speed because:
(A) no force of friction due to air acting on it
(B) its mass is zero in space
(C) no force of gravitation acts on it
(D) no force of friction due to earth acting on it
Correct Answer: (C)
23. The force of freely falling body is directly proportional to:
(A) mass of body
(B) acceleration of body
(C) velocity of body
(D) both (A) and (B)
Correct Answer: (D)
24. Which of the following are vector quantities:
(A) momentum
(B) velocity
(C) force
(D) all of the above
Correct Answer: (D)
25. Force remaining constant, if the mass of body increases, its acceleration is likely to:
(A) increase
(B) remain same
(C) decrease
(D) sometimes increases and sometimes decreases
Correct Answer: (C)
26. A force F produces an acceleration ‘a’ in a body. The same force produced and acceleration 4a in another body. The mass of other body is:
(A) four times the mass of the first body
(B) four times less the mass of other body
(C) mass does not play role
(D) none of the above
Correct Answer: (B)
27. A force F acts on a stationary body for the time t. The distance covered by the body ‘S’ will be proportional to:
(A) t
(B)1/t
(C) t2
(D)1/t²
Correct Answer: (C)
28. A body P has mass 2m and velocity 5v. Another body Q has mass 8m and velocity 1.25v. The ratio of momentum of P and Q is:
(A) 2 : 1
(B) 1 : 1
(C) 1 : 2
(D) 3 : 2
Correct Answer: (B)
29. According to the third law of motion, action and reaction
(A) always act on the same body
(B) always act on different bodies in opposite directions
(C) have same magnitude and directions
(D) act on either body at normal to each other
Correct Answer: (B)
30. Rocket works on the principle of conservation of
(A) mass
(B) energy
(C) momentum
(D) velocity
Correct Answer: (C)
31. If the mass of a body is doubled and its velocity becomes half, then the linear momentum of the body will
(A) remain same
(B) become double
(C) become half
(D) become four times.
Correct Answer: (A)
32. A man is standing on a boat in still water. If he walks towards the shore, then the boat will
(A) move away from the shore
(B) move towards the shore
(C) remain stationary
(D) none of these
Correct Answer: (A)
33. A bullet of mass A and velocity B is fired into a wooden block of mass C. If the bullet gets embedded in the wooden block, then the magnitude of velocity of the system just after the collision will be
Correct Answer: (D)
34. The masses of two bodies are in ratio 5 : 6 and their velocities are in ratio 1 : 2. Then their linear momentum will be in the ratio
(A) 5 : 6
(B) 1 : 2
(C) 12 : 5
(D) 5 : 12
Correct Answer: (D)
35. A bullet of mass 0.01 kg is fired from a rifle. The bullet takes 0.003 s to move through the barrel and leaves with a velocity of 300 ms–1 .The acceleration acting on the bullet is
(A) 10,000 ms–2
(B) 100,000 ms–2
(C) 1000,000 ms–2
(D) 1000 ms–2
Correct Answer: (B)
36. A cracker at rest explodes into two equal parts. These parts will move in:
(A) opposite direction with different velocities
(B) same direction with different velocities
(C) same direction with same velocities
(D) opposite direction with same velocities
Correct Answer: (D)
37. A body is moving with a constant momentum. The motion of the body is:
(A) uniform velocity
(B) accelerated
(C) de-accelerated
(D) none of the above.
Correct Answer: (A)
38 The principle of conservation of linear momentum states that in a system it
(A) cannot be changed
(B) can be changed, if internal forces act on it
(C) can be changed, if external forces act on it
(D) none of the above
Correct Answer: (C)
| Chapter -1 Matter in Our Surroundings |
| Chapter – 2 Is Matter Around Us Pure? |
| Chapter -3 Atoms and Molecules |
| Chapter -4 Structure of the Atom |
| Chapter -5 The Fundamental Unit of Life |
| Chapter -6 Tissues |
| Chapter -7 Motion |
| Chapter -8 Force and Laws of Motion |
| Chapter -9 Gravitation |
| Chapter -10 Work and Energy |
| Chapter -11 Sound |
| Chapter -12 Improvement of Food Resources |