Solving the Work, Energy and Power Multiple Choice Questions of Class 11 Physics Chapter 6 MCQ can be of extreme help as you will be aware of all the concepts. These MCQ Questions on Work, Energy and Power Class 11 with answers pave for a quick revision of the Chapter thereby helping you to enhance subject knowledge. Have a glance at the MCQ of Chapter 6 Physics Class 11 and cross-check your answers during preparation.

Question 1.
When a force of 50 N acts on a body, the body is displaced through a distance of 3 m in a direction normal to the direction of the force. The work done by the force
(a) 150 J
(b) 1470 J
(c) Zero
(d) -150 J

Answer

Answer: (c) Zero

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Question 2.
A body of mass 20 kg is initially at a height of 3 m above the ground. It is lifted to a height of 2 m from that position. Its increase in potential energy is
(a) 100 J
(b) 392 J
(c) 60 J
(d) -100 J

Answer

Answer: (b) 392 J

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Question 3.
A wooden cube having mass 10 kg is dropped from the top of a building . After 1 s, a bullet of mass 20 g fired at it from the ground hits the block with a velocity of 1000 m/s at an angle of 30° to the horizontal moving upwards and gets imbedded in the block . The velocity of the block/bullet system immediately after the collision is
(a) 17 m/s
(b) 27 m/s
(c) 52 m/s
(d) 10 m/s

Answer

Answer: (a) 17 m/s

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Question 4.
A body of mass 10 kg is moved parallel to the ground, through a distance of 2 m. The work done against gravitational force is
(a) 196 J
(b) -196 J
(c) 20 J
(d) zero

Answer

Answer: (d) zero

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Question 5.
A quantity of work of 1000 J is done in 2 seconds. The power utilised is
(a) 998 W
(b) 1002 W
(c) 2000 W
(d) 500 W

Answer

Answer: (d) 500 W

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Question 6.
A body of mass 1 kg travels with a velocity of 10 m/s, this a wall and rebounds. If 50% of its initial energy is wasted as heat, its kinetic energy at the instant of rebounding is
(a) 20 J
(b) 60 J
(c) 50 J
(d) 25 J

Answer

Answer: (d) 25 J

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Question 7.
A marble moving with some velocity collides perfectly elastically head-on with another marble at rest having mass 1.5 times the mass of the colliding marble. The percentage of kinetic energy by the colliding marble after the collision is
(a) 4
(b) 25
(c) 44
(d) 67

Answer

Answer: (a) 4

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Question 8.
A particle of mass m is moving in a horizontal circle of radius r under a centripetal force given by (-kr²) where k is a constant , then
(a) the total energy of the particle is (- k/2r)
(b) the kinetic energy of the particle is (k/r)
(c) the potential energy of the particle is (k/2r)
(d) the kinetic energy of the particle is (- k/r)

Answer

Answer: (a) the total energy of the particle is (- k/2r)

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Question 9.
A sphere of mass m moving with a constant velocity u hits another stationary sphere of the same mass. If e is the coefficient of restitution, then the ratio of velocity of the two spheres after the collision will be
(a) 1 – e / 1 + e
(b) 1 + e / 1 – e
(c) e + 1 / e – 1
(d) e – 1 / e + 1

Answer

Answer: (a) 1 – e / 1 + e

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Question 10.
Two masses 1 g and 4 g are moving with equal kinetic energles. The ratio of the magnitudes of their linear momenta is
(a) 4 : 1
(b) 0 : 1
(c) 1 : 2
(d) 1 : 6

Answer

Answer: (c) 1 : 2

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Question 11.
A ball is dropped from a height of 1 m. If the coefficient of restitution between the surface and ball is 0.6, the ball rebounds to a height of
(a) 0.6 m
(b) 0.4 m
(c) 1 m
(d) 0.36 m

Answer

Answer: (d) 0.36 m

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Question 12.
A wooden cube having mass 10 kg is dropped from the top of a building. After 1 s, a bullet of mass 20 g fired at it from the ground hits the block with a velocity of 1000 m/s at an angle of 30° to the horizontal moving upwards and gets imbedded in the block. The velocity of the block/bullet system immediately after the collision is
(a) 17 m/s
(b) 27 m/s
(c) 52 m/s
(d) 10 m/s

Answer

Answer: (a) 17 m/s

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Question 13.
A bullet fired into a fixed target loses half of its velocity after penetrating 3 cm. How much further will it penetrate before coming to rest assuming that it faces constant resistance to motion?
(a) 2.0 cm
(b) 3.0 cm
(c) 1.0 cm
(d) 1.5 cm

Answer

Answer: (c) 1.0 cm

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Question 14.
A body of mass 5 kg is initially at a height of 10 m above the ground. It is then moved to another place 40 m from this position in the same horizontal level. Its increase in potential energy is
(a) 200 J
(b) 1960 J
(c) Zero
(d) -200 j

Answer

Answer: (c) Zero

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Question 15.
A body of mass 20 kg falls through a vertical height of 3 m. The work done by the gravitational force is
(a) -588 J
(b) 588 J
(c) 60 J
(d) -60 J

Answer

Answer: (b) 588 J

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Question 16.
A body of mass 1 kg travels with a velocity of 10 m/s, this a wall and rebounds. If 50% of its initial energy is wasted as heat, its kinetic energy at the instant of rebounding is
(a) 20 J
(b) 60 J
(c) 50 J
(d) 25 J

Answer

Answer: (d) 25 J

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Question 17.
An electric heater of rating 1000 W is used for 5 hrs per day for 20 days. The electrical energy utilised is
(a) 150 kWh
(b) 200 kWh
(c) 100 kWh
(d) 300 kWh

Answer

Answer: (c) 100 kWh

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Question 18.
A body of mass 20 kg falls vertically through a height of 10 m. Its loss of potential energy is
(a) 300 J
(b) 4000 J
(c) 1000 J
(d) 1960 J

Answer

Answer: (d) 1960 J

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Question 19.
A body of mass 10 kg is travelling with uniform speed of 5 m/s. Its kinetic energy is
(a) 25 J
(b) 125 J
(c) 1250 J
(d) 1000 J

Answer

Answer: (b) 125 J

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Question 20.
A quantity of work of 1000 J is done in 2 seconds. The power utilised is
(a) 998 W
(b) 1002 W
(c) 2000 W
(d) 500 W

Answer

Answer: (d) 500 W

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