MCQ Questions for Class 11 Physics Chapter 5 Laws of Motion

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MCQ Questions for Class 11 Physics Chapter 5 Laws of Motion

Q.1. Inertia is the property of a body linked to tendency of a body
(a) to change its position
(b) to change its direction
(c) to change the momentum
(d) to resist any change in its state

Answer Answer: (d) Inertia is defined as the ability of a body to oppose any change in its state of rest or of uniform motion.

Q.2. Force depends on
(a) change in momentum
(b) how fast the change in momentum is brought about
(c) Both (a) & (b)
(d) None of these

Answer Answer: (c)

Q.3. Physical independence of force is a consequence of
(a) third law of motion
(b) second law of motion
(c) first law of motion
(d) all of these

Answer Answer: (c) Newton’s first law of motion is related to the physical independence of force.

Q.4. In an explosion, a body breaks up into two pieces of unequal masses. In this
(a) both parts will have numerically equal momentum
(b) lighter part will have more momentum
(c) heavier part will have more momentum
(d) both parts will have equal kinetic energy

Answer Answer: (a)

Q.5. Which motion does not require force to maintain it ?
(a) Uniform circular motion
(b) Elliptical motion
(c) Uniform straight line motion
(d) Projectile motion

Answer Answer: (c)

Q.6. Newton’s first law of motion describes the
(a) energy
(b) work
(c) inertia
(d) moment of inertia

Answer Answer: (c) Newton’s first law of motion defines the inertia of body. It states that every body has a tendency to remain in its state (either rest or motion) due to its inertia.

Q.7. A ball is travelling with uniform translatory motion. This means that
(a) it is at rest.
(b) the path can be a straight line or circular and the ball travels with uniform speed.
(c) all parts of the ball have the same velocity (magnitude and direction) and the velocity is constant.
(d) the centre of the ball moves with constant velocity and the ball spins about its centre uniformly.

Answer Answer: (c)

Q.8. A jet engine works on the principle of
(a) conservation of mass
(b) conservation of energy
(c) conservation of linear momentum
(d) conservation of angular momentum

Answer Answer: (c)

Q.9. A reference frame attached to the earth
(a) is an inertial frame by definition
(b) cannot be an inertial frame because earth is revolving round the sun
(c) is an inertial frame because Newton’s laws are applicable
(d) is an inertial frame because the earth is rotating about its own axis

Answer Answer: (b) The frame of reference which are at rest or in uniform motion are called inertial frames while frames which are accelerated with respect to each other are non– inertial frames. Spinning or rotating frames are accelerated frame, hence these are non-inertial frames.

Q.10. A man is standing at the centre of frictionless pond of ice. How can he get himself to the shore?
(a) By throwing his shirt in vertically upward direction
(b) By spitting horizontally
(c) He will wait for the ice to melt in pond
(d) Unable to get at the shore

Answer Answer: (b)

Q.11. An object will continue moving uniformly when
(a) the resultant force on it is increasing continuously
(b) the resultant force is at right angles to its rotation
(c) the resultant force on it is zero
(d) the resultant force on it begins to decrease

Answer Answer: (c) The body will continue accelerating until the resultant force acting on the body becomes zero.

Q.12. No force is required for
(a) an object moving in straight line with constant velocity
(b) an object moving in circular motion
(c) an object moving with constant acceleration
(d) an object moving in elliptical path.

Answer Answer: (a) No force is required for an object moving in straight line with constant velocity or for non acceleration motion.

Q.13. External agencies like gravitational and magnetic forces …X… exerts force on a body from a distance. Here, X refers to
(a) can
(b) cannot
(c) never
(d) None of these

Answer Answer: (a) External agencies like gravitational and magnetic forces can exert force on body from distance. When ball is released from some height. Earth exerts gravitational force from distance, ball moves faster with time.

Q.14. The direction of impulse is
(a) same as that of the net force
(b) opposite to that of the net force
(c) same as that of the final velocity
(d) same as that of the initial velocity

Answer Answer: (a)

Q.15. When a body is stationary
(a) there is no force acting on it
(b) the force acting on it is not in contact with it
(c) the combination of forces acting on it balances each other
(d) the body is in vacuum

Answer Answer: (c)

Q.16. If a stone is thrown out of an accelerated train, then acceleration of the stone at any instant depends on
(a) force acting on it at that instant
(b) acceleration of the train
(c) Both (a) & (b)
(d) None of these

Answer Answer: (a)

Q.17. According to Galileo’s experiment for a double inclined plane, if slope of second plane is zero and planes are smooth, then a ball is released from rest on one of the planes rolls down and move on the second plane …X… distance. Here, X is
(a) zero
(b) infinite
(c) equal to length of first plane
(d) None of these

Answer Answer: (b)

Q.18. Impulse equals
(a) rate of change of momentum
(b) change in momentum
(c) momentum multiplied by time
(d) rate of change of force

Answer Answer: (b)

Q.19. Swimming is possible on account of
(a) first law of motion
(b) second law of motion
(c) third law of motion
(d) newton’s law of gravitation

Answer Answer: (c) Swimming is a result of pushing water in the opposite direction of the motion.

Q.20. Newton’s second and third laws of motion lead to the conservation of
(a) linear momentum
(b) angular momentum
(c) potential energy
(d) kinetic energy

Answer Answer: (a) Newton’s second and third laws of motion leads to the conservation of linear momentum.

Q.21. Rocket engines lift a rocket from the earth surface, because hot gases with high velocity
(a) push against the air
(b) push against the earth
(c) react against the rocket and push it up
(d) heat up the air which lifts the rocket.

Answer Answer: (c) Hot gases with high velocity react against the rocket and push it up.

Q.22. The acceleration of an astronaut is zero once he steps out of his accelerated spaceship in the intersteller space. this statement is in accordance with
(a) Newton’s second law of motion
(b) Newton’s first law of motion
(c) Newton’s third law of motion
(d) All of these

Answer Answer: (b) Since no nearby stars are there to exert gravitational force on the astronaut, so the net force acting on him is zero when he moves out of the spaceship. Thus in accordance with first law of motion the acceleration of astronaut will be zero.

Q.23. A body whose momentum is constant must have constant
(a) velocity
(b) force
(c) acceleration
(d) All of the above

Answer Answer: (a) It works on the principle of conservation of linear momentum.

Q.24. Law of conservation of momentum follows from
(a) Newton’s first law of motion
(b) Newton’s second law of motion
(c) Newton’s third law of motion
(d) Both (b) & (c)

Answer Answer: (d)

Q.25. A cannon after firing recoils due to
(a) conservation of energy
(b) backward thrust of gases produced
(c) Newton’s third law of motion
(d) Newton’s first law of motion

Answer Answer: (c)

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