# Class 11 Physics Chapter 6 Work, Energy and Power MCQ Questions with Answer

Work Energy and Power Class 11 MCQ is one of the best strategies to prepare for the CBSE Class 11 Board exam. If you want to complete a grasp concept or work on one’s score, there is no method except constant practice. Students can improve their speed and accuracy by doing more MCQ on Work Energy and Power Class 11, which will help them all through their board test.

## Work Energy and Power Class 11 MCQ Questions with Answer

Class 11 Physics MCQ with answers are given here to Chapter 6 Work Energy and Power. These MCQs are based on the latest CBSE board syllabus and relate to the latest Class 11 Physics syllabus. By Solving these Class 11 MCQs, you will be able to analyze all of the concepts quickly in the chapter and get ready for the Class 11 Annual exam.

Learn Class 11 Work Energy and Power MCQs with answers pdf free download according to the latest CBSE and NCERT syllabus. Students should prepare for the examination by solving CBSE Class 11 Physics Work Energy and Power MCQ with answers given below

Question 1. A light and a heavy body have equal momentum. Which one has greater K.E.?
(a) The lighter body
(b) The heavier body
(c) Both have equal K.E.
(d) Data given is incomplete

A

Question 2. A particle of mass m has momentum p. Its kinetic energy will be
(a) mp
(b) p2m
(c) p2 m
(d) 2 2 p m

D

Question 3. When the force retards the motion of body, the work done is
(a) zero
(b) negative
(c) positive
(d) Positive or negative depending upon the magnitude of force and displacement

B

Question 4. A uniform force of (3iˆ+ ˆj) newton acts on a particle of mass 2 kg. The particle is displaced from position (2\$i + k\$) meter to position (4\$i + 3\$j – k\$) meter. The work done by the force on the particle is
(a) 6 J
(b) 13 J
(c) 15 J
(d) 9 J

D

Question 5. A boy pushes a toy box 2.0 m along the floor by means of a force of 10 N directed downward at an angle of 60º to the horizontal. The work done by the boy is
(a) 6 J
(b) 8 J
(c) 10 J
(d) 12 J

C

Question 6. A man pushes a wall and fails to displace it, he does
(a) negative work
(b) positive but not maximum work
(c) no work at all
(d) maximum positive work

C

Question 7. Kinetic energy, with any reference, must be
(a) zero
(b) positive
(c) negative
(d) both (b) and (c)

B

Question 8. The position of a particle of mass 4 g, acted upon by a constant force is given by x = 4t2 + t, where x is in metre andt in second. The work done during the first 2 seconds is
(a) 128 mJ
(b) 512 mJ
(c) 576 mJ
(d) 144 mJ

C

Question 9. A particle is taken round a circle by application of force. The work done by the force is
(a) positive non–zero
(b) negative non–zero
(c) Zero
(d) None of these

C

Question 10. The work done in stretching a spring of force constant k from length l1 and l2 is
(a) k( 2 ) 1 2 l 2 – l
(b) k( ) 2 1 2 1 2 l 2 – l
(c) k(l 2 – l1)
(d) ( ) 2 k l 2 + l1

B

Question 11. A boy carrying a box on his head is walking on a level road from one place to another is doing no work. This statement is
(a) correct
(b) incorrect
(c) partly correct
(d) cannot say

A

Question 12. No work is done if
(a) displacement is zero
(b) force is zero
(c) force and displacement are mutually perpendicular
(d) All of these

D

Question 13. A ball of mass m moves with speed V and strikes a wall having infinite mass and it returns with same speed, then the workdone by the ball on the wall is
(a) zero
(b) mvJ
(c) m/v J
(d) v/m J

A

Question 14. A body of mass 3 kg is under a constant force which causes a displacement s in metre in it, given by the relation t2 3 s = 1 ,is in second. Work done by the force in 2 second is
(a) J 8 3
(b) J 3 8
(c) J 5 19
(d) J 19 5

B

Question 15. A particle moves under the effect of a force F = cx from x = 0 to x = x1, the work done in the process is
(a) 2 cx1
(b) 2 1 1 cx 2
(c) 2 2 cx1
(d) zero

B

Question 16. A particle moving in the xy plane undergoes a displacement of sr = (2iˆ +3 ˆj) while a constant force F = (5iˆ+2 ˆj) r N acts on the particle. The work done by the force F is
(a) 17 joule
(b) 18 joule
(c) 16 joule
(d) 15 joule

C

Question 17. Calculate the work done on the tool by F r if this displacement is along the straight line y = x that connects these two points.
(a) 2.50 J
(b) 500 J
(c) 50.6 J
(d) 2 J

C

Question 18. Calculate the work done on the tool by F r if the tool is first moved out along the x-axis to the point x = 3.00m, y = 0 and then moved parallel to the y-axis to x = 3.00m, y = 3.00
(a) 67.5 J
(b) 85 J
(c) 102 J
(d) 7.5 J

A

Question 19. A body is moved along a straight line by a machine delivering a constant power. The distance moved by the body in time ‘t’ is proportional to
(a) t3/4
(b) t3/2
(c) t1/4
(d) t1/2

B

Question 20. A body projected vertically from the earth reaches a height equal to earth’s radius before returning to the earth. The power exerted by the gravitational force is greatest
(a) at the highest position of the body
(b) at the instant just before the body hits the earth
(c) it remains constant all through
(d) at the instant just after the body is projected

B

Question 21. A particle describe a horizontal circle of radius 0.5 m with uniform speed. The centripetal force acting is 10 N. The work done in describing a semicircle is
(a) zero
(b) 5 J
(c) 5 p J
(d) 10 p J

A

Question 22. The engine of a vehicle delivers constant power. If the vehicle is moving up the inclined plane then, its velocity,
(a) must remain constant
(b) must increase
(c) must decrease
(d) may increase, decrease or remain same.

A

Question 23. A cord is used to lower vertically a block of mass M, a distance d at a constant downward acceleration of g/4. The work done by the cord on the block is
(a) Mg d 4
(b) 3Mg d 4
(c) 3Mg d 4 –
(d) Mg d

C

Question 24. Assertion : A man rowing a boat upstream is at rest with respect to the bank. He is doing no external work. Reason : Work done by constant force, W = F s cos q.
(a) Assertion is correct, reason is correct; reason is a correct explanation for assertion.
(b) Assertion is correct, reason is correct; reason is not a correct explanation for assertion
(c) Assertion is correct, reason is incorrect
(d) Assertion is incorrect, reason is correct.

A

Question 25. Assertion : The work done in moving a body over a closed loop is zero for every force in nature. Reason : Work done depends on nature of force.
(a) Assertion is correct, reason is correct; reason is a correct explanation for assertion.
(b) Assertion is correct, reason is correct; reason is not a correct explanation for assertion
(c) Assertion is correct, reason is incorrect
(d) Assertion is incorrect, reason is correct.

B

Whoever needs to take the CBSE Class 11 Board Exam should look at this MCQ. To the Students who will show up in CBSE Class 11 Physics Board Exams, It is suggested to practice more and more questions. Aside from the sample paper you more likely had solved. These Work Energy and Power Class 11 MCQ are ready by the subject specialists themselves.

Question 26. A force acts on a 30 g particle in such a way that the position of the particle as a function of time is given by x = 3t – 4t2 + t3, where x is in metres and t is in seconds. The work  one during the first 4 seconds is
(a) 576 mJ
(b) 450 mJ
(c) 490 mJ
(d) 530 mJ

A

Question 27. A small body is projected in a direction inclined at 45º to the horizontal with kinetic energy K. At the top of its flight, its kinetic energy will be
(a) Zero
(b) K/2
(c) K/4
(d) K / 2

B

Question 28. A bomb of mass 9 kg explodes into the pieces of masses 3 kg and 6 kg. The velocity of mass 3 kg is 16 m/s. The kinetic energy of mass 6 kg in joule is
(a) 96
(b) 384
(c) 192
(d) 768

C

Question 29. If a motorcyclist skids and stops after covering a distance of 15 m. The stopping force acting on the motorcycle by the road is 100 N, then the work done by the motorcycle on the road is
(a) 1500 J
(b) –1500 J
(c) 750J
(d) Zero

D

Question 30. A ball moves in a frictionless inclined table without slipping. The work done by the table surface on the ball is
(a) positive
(b) negative
(c) zero
(d) None of these

C

Question 31. A spring of force constant 800 N/m has an extension of 5 cm. The work done in extending it from 5 cm to 15 cm is
(a) 16 J
(b) 8 J
(c) 32 J
(d) 24 J.

B

Question 32. A body moves a distance of 10 m along a straight line under the action of a force of 5 newtons. If the work done is 25 joules, the angle which the force makes with the direction of motion of body is
(a) 0º
(b) 30º
(c) 60º
(d) 90º

C

Question 33. Two bodies of masses 4 kg and 5 kg are moving with equal momentum. Then the ratio of their respective kinetic energies is
(a) 4 : 5
(b) 2 : 1
(c) 1 : 3
(d) 5 : 4

D

Question 34. A spring of spring constant 5 × 103 N/m is stretched initially by 5 cm from the unstretched position. Then the work required to stretch it further by another 5 cm is
(a) 18.75 J
(b) 25.00 J
(c) 6.25 J
(d) 12.50 J

A

Question 35. The …X… energy V(x) of the spring is said to be zero when block and spring system is in the …Y… position. Here, X and Y refer to
(a) potential, equilibrium
(b) kinetic, equilibrium
(c) mechanical, equilibrium
(d) vibrational, left

A

Question 36. If stretch in a spring of force constant k is tripled then the ratio of elastic potential energy in the two cases will be
(a) 9 : 1
(b) 1 : 6
(c) 3 : 1
(d) 1 : 3

A

Question 37. According to work-energy theorem, the work done by the net force on a particle is equal to the change in its
(a) kinetic energy
(b) potential energy
(c) linear momentum
(d) angular momentum

A

Question 38. Work done by a conservative force is positive if
(a) P.E. of the body increases
(b) P.E. of the body decreases
(c) K.E. of the body increases
(d) K.E. of the body decreases

B

Question 39. A long string is stretched by 2 cm and the potential energy is V. If the spring is stretched by 10 cm, its potential energy will be
(a) V / 25
(b) V/5
(c) 5 V
(d) 25 V

D

Question 40. The potential energy of a conservative system is given by U = ay2 – by, where y represents the position of the particle and a as well as b are constants. What is the force acting on the system ?
(a) – ay
(b) – by
(c) 2ay – b
(d) b – 2ay

D

Question 41. If a shell fired from a cannon, explodes in mid air, then
(a) its total kinetic energy increases
(b) its total momentum increases
(c) its total momentum decreases
(d) None of these

A

Question 42. Total ….X…. energy of a system is conserved, if the forces, doing work on it, are …..Y….. . Here, X and Y refer to
(a) conservative, mechanical
(b) mechanical, conservative
(c) mechanical, non-conservative
(d) kinetic, conservative

B

Question 43. One man takes 1 min. to raise a box to a height of 1 metre and another man takes 1/2 min. to do so. The energy of the
(a) two is different
(b) two is same
(c) first is more
(d) second is more

B

Question 44. If a force F is applied on a body and it moves with a velocity V, the power will be
(a) F × v
(b) F/v
(c) F/v2
(d) F × v2

A

Question 45. A bullet is fired and gets embedded in block kept on table. If table is frictionless, then      C
(a) kinetic energy gets conserved
(b) potential energy gets conserved
(c) momentum gets conserved
(d) both (a) and (c)

Question 46. The speed of an object of mass m dropped from an inclined plane (frictionless), at the bottom of the plane, depends on:
(a) height of the plane above the ground
(b) angle of inclination of the plane
(c) mass of the object
(d) All of these

A

Question 47. A ball dropped from a height of 2m reaches to a height of 1.5m before hitting the ground. Then the percentage of potential energy lost is
(a) 25
(b) 30
(c) 50
(d) 100

A

Question 48. Four particles given, have same momentum. Which has maximum kinetic energy
(a) Proton
(b) Electron
(c) Deutron
(d) a-particles

B

Question 49. If the momentum of a body is increased by 50%, then the percentage increase in its kinetic energy is
(a) 50%
(b) 100%
(c) 125%
(d) 200%

C

Question 50. The potential energy of a system increases if work is done
(a) upon the system by a non conservative force
(b) by the system against a conservative force
(c) by the system against a non conservative force
(d) upon the system by a conservative force

D

Question 51. A metallic wire of length L metre extends by l metre when stretched by suspending a weight Mg from it. The mechanical energy stored in the wire is
(a) 2 Mg l
(b) Mg l
(c) Mg 2 l
(d) Mg 4 l

C

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