## Class 11 Physics Objective Chapter – 6 Work, Energy and Power

Here we are providing NCERT Class 11 Physics Objective Chapter – 6 Work, Energy and Power Chapter Wise MCQs for board exam is very important for board exam preparation. This book explains all the concepts and topics in very simple language that the students can easily understand the complex subjects also. This NCERT Class 11 Physics MCQs Chapter – 6 Work, Energy and Power Chapter consist all important topic regarding NCERT Class 11 Physics Objective Chapter – 6 Work, Energy and Power. This book basically covers all the major and minor elements that together form a democratic government. Topics like power-sharing, federalism, democracy and diversity, political parties, consequences of democracy, challenges to democracy etc. have been discussed in the NCERT Class 11 Physics Objective Chapter – 6 Work, Energy and Power. The question papers in CBSE board exams are generally based on the latest NCERT books. Hence, students must follow the NCERT book to prepare effectively for their Class 11 Physics exam. If you want color notes then click here

Class 11 Physics Objective Chapter – 6 Work, Energy and Power

1. The rate of doing work is called ——————-

( a ) Force

( b ) Acceleration

( c ) Power

( d ) Displacement

Ans:- (c)

2. A man of 60 kg weight is standing at rest on a platform. He jumps up vertically a distance of 1 m and the platform at the same instant moves horizontally forward with the result that the man lands 1 meter behind the point on the platfrom from where the took the jump the total work done by the man at the instant he lands is

( a ) 300 J

( b ) 150 J

( c ) 600 J

( d ) zero

Ans:- (c)

3. The quantities which are involved in scalar product are

( a ) Both vectors

( b ) Both scalars

( c ) One scalar and other vector

( d ) None

Ans:- (a)

4. 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 ) angular momentum

( c ) linear momentum

( d ) potential energy

Ans:- (a)

5. Two particles A and B having mass m each and charge q1 and −q2 respectively, are connected at the ends of a non conducting flexible and inextensible string of the length l. The particle A is fixed and B is whirled along a vertical circle with centre at A. If a vertically upward electric field of strength E exists in the space, then for minimum velocity of particle B:

( a ) The tension force in string at lowest point is zero

( b ) The tension force at the lowest point is non-zero

( c ) The tension force at the highest point is zero

( d ) The work done by interaction force between particles A and B is non-zero

Ans:- (a)

6. A bullet is fired horizontally and gets embedded in a block kept on a table. If the table is frictionless, then

( a ) only momentum is conserved.

( b ) only potential energy is conserved.

( c ) only K.E. is conserved.

( d ) both (a) and (b).

Ans:- (d)

7. Which is the type of collision in which both the linear momentum and the kinetic energy of the system remain conserved?

( a ) Inelastic Collision

( b ) Elastic Collision

( c ) Destructive collision

( d ) None of the options

Ans:- (b)

8. A uniform chain of length 2 m is kept on a table such that a length of 60 cm hangs freely from the edge of the table. The total mass of the chain is 4 kg. What is the work done in pulling the entire chain on the table

( a ) 7.2 J

( b ) 3.6 J

( c ) 120 J

( d ) 1200 J

Ans:- (b)

9.  The scalar product of two vectors is the

( a ) Vector

(b) Scalar

(c) Tensor

(d) None

Ans:- (b)

10. 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

Ans:- (a)

11. A constant force of 5N is applied on a block of mass 20 kg for a distance of 2.0 m, the kinetic energy acquired by the block is

( a ) 20 J

( b ) 15 J

( c ) 10 J

( d ) 5 J

Ans:- (c)

12. 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

Ans:- (a)

13. Collision between marble balls is which type of collision

( a ) Inelastic Collision

( b ) Elastic Collision

( c )  Destructive collision

( d ) None of the options

Ans:- (b)

14. 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

Ans:- (b)

15. The quantities which are involved in vector product are

(a) Both scalar

(b) Both vector

(c) One scalar one vector

(d) None

Ans:- (b)

16. Kinetic energy, with any reference, must be

(a) positive

(b) zero

(c) negative

(d) None of these

Ans:- (a)

17. Two perfectly elastic objects AA and BB of identical mass are moving with velocities 15 m/s and 10m/s respectively collide along the direction of line joining them. Their velocities after collision are respectively:

( a ) 10m/s, 15 m/s

( b ) 20 m/s, 5m/s

( c )  0 m/s, 25 m/s

( d ) 5 m/s, 20 m/s

Ans:- (a)

18. A ball is dropped from a height of 1 m. If the coeffcient 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

Ans:- (d)

19. The energy possessed by the body by virtue of its motion is known as?

( a ) Chemical energy

( b ) Thermal energy

( c ) Potential energy

( d ) Kinetic energy

Ans:- (d)

20. 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

Ans:- (b)

21. The vector product of two vectors is

(a) Vector

(b) Scalar

(c) Tensor

(d) None

Ans:- (a)

22. Work done by a conservative force is positive if

(a) P.E. of the body decreases

(b) K.E. of the body increases

(c) K.E. of the body decreases

(d) P.E. of the body increases

Ans:- (a)

23. A heavy stone hanging from a massless string of length 15m is projected horizontally with speed 147 m/s. The speed of the particle at the point where the tension in the string equals the weight of the particle is

( a ) 10 m/s

( b ) 7 m/s

( c ) 12 m/s

( d ) None of these

Ans:- (d)

24. A proton is kept at rest. A positively charged particle is released from rest at a distance d in its field. Consider two experiments; one in which the charged particles is also a proton and in another, a positron. In the same time t, the work done on the two moving charged particles is

( a ) the same as the same force law is involved in the two experiments

( b ) less for the case of a positron, as the positron moves away more rapidly and the force on it weakens

( c ) more for the case of a positron, as the positron moves away from a larger distance

( d ) same as the work done by charged particle on the stationary proton

Ans:- (c)

25. Find the potential energy stored in a ball of 5 kg placed on the ground of 3m.

( a ) 121.20 J

( b ) 147.15 J

( c ) 227.31 J

( d ) 182.21 J

Ans:- (b)

26. 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

Ans:- (d)

27. When the linear momentum of a particle is increased by 1% its kinetic energy increases by x%. When the kinetic energy of the particle is increased by 300%, its linear momentum increases by y%. The ratio of y to x is

(a) 300

(b) 150

(c) 100

(d) 50

Ans:- (d)

28.  The scalar product is given by

(a) A•B = AB sinx

(b) A×B = AB sinx

(c) A•B = AB cosx

(d) A×B = AB cosx

Ans:- (c)

29. 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

Ans:- (a)

30. A block of mass 1kg is free to move along the X-axis. It is at rest and from time  t=0 onwards it is subjected to a time-dependent force F(t ) in the X-direction. The force F(t ) varies with t as shown in figure. The kinetic energy of the block at t=4s is

( a ) 1J

( b ) 2J

( c ) 3J

( d ) 0J

Ans:- (d)

31. A bicyclist comes to a skidding stop in 10 m. During this process, the force on the bicyclist due to the road is 200 N and is directly opposed to the motion. The work done by the cycle on the road is

( a ) +2000 J

( b ) -200 J

( c ) zero

( d ) -20,000 J

Ans:- (c)

32. What is the power utilized when work of 1000 J is done in 2 seconds?

( a ) 100 W

( b ) 200 W

( c ) 20 W

( d ) 500 W

Ans:- (d)

33. A solid cylinder of length 1 m and diameter of cross section y 100 cms is first placed with its axis vertical its then slowly inclined till its axis is horizontal. The loss in its potential energy if the mass of the cylinder is 10 kg is

(a) 5g J

(b) 10g J

(c) Zero

(d) g J

Ans:- (c)

34. A body of mass 10 kg moving at a height of 2 m, with uniform speed of 2 m/s. Its total energy is

(a) 316 J

(b) 216 J

(c) 116 J

(d) 392 J

Ans:- (b)

35. Scalar product is

(a) Commutative

(b) Not commutative

(c) Both a and b

(d) None

Ans:- (a)

36. Which of the following must be known in order to determine the power output of an automobile?

(a) Work performed and elapsed time of work

(b) Force exerted and distance of motion

(c) Mass and amount of work performed

(d) Final velocity and height

Ans:- (a)

37.  The work performed on an object does not depend upon

( a ) the displacement.

( b ) the force applied.

( c ) the angle at which the force is applied to the displacement

( d ) initial velocity of the object.

Ans:- (d)

38. An electron and a proton are moving under the influence of mutual forces. In calculating the change in the kinetic energy of the system during motion, one ignores the magnetic force of one on another. This is because

( a ) the two magnetic forces are equal and opposite, so they produce no net effect

( b ) the magnetic forces do no work on each particle

( c ) the magnetic forces do equal and opposite work on each particle

( d ) the magnetic forces are necessarily negligible

Ans:- (b)

39. Which one has higher kinetic energy? Both light and heavy bodies have equal momentum.

( a ) Heavy body

( b ) Light body

( c ) Both

( d ) None of the option

Ans:- (b)

40. Two masses 1 g and 4 g are moving with equal kinetic energies. The ratio of the magnitudes of their linear momenta is

(a) 4 : 1

(b) 1 : 2

(c) 0 : 1

(d) 1 : 6

Ans:- (b)

41. A body of mass 10 kg is initially at a height of 20 m above the ground. It falls to a height of 5 m above the ground. Its potential energy in the new position is

(a) 490 J

(b) 50 J

(c) 100 J

(d) 300 J

Ans:- (a)

42.  Scalar product is commutative means

a) A•B = A•B

(b) A•B = B•A

(c) Both a and b

(d) None

Ans:- (b)

43. A vehicle is moving with a uniform velocity on a smooth horizontal road, then power delivered by its engine must be

(a) increasing

(b) zero

(c) uniform

(d) decreasing

Ans:- (a)

44.After how much time collision between the blocks will not take place practically:

( a ) 8 sec

( b ) 16 sec

( c ) 12 sec

( d ) Infinite

Ans:- (c)

45. . A body of mass 0.5 kg travels in a straight line with velocity v = ax3/2 where a = 5 m-1/2s-1. The work done by the net force during its displacement from x = 0 to x = 2 m is

( a ) 1.5 J

( b ) 50 J

( c ) 10 J

( d ) 100 J

Ans:- (b)

46. . An electric heater of rating 1000 W is used for 5 hrs per day for 20 days. What is the electrical energy utilized?

( a ) 100 kWh

( b ) 200 kWh

( c ) 120 kWh

( d ) 500 kWh

Ans:- (a)

47. A body of mass 100 kg falls from a height of 10 m. Its increase in kinetic energy is

(a) 9800 J

(b) 1000 J

(c) 5000 J

(d) 3000 J

Ans:- (a)

48. An isolated particle of mass m is moving in a horizontal plane (x-y), along the x-axis, at a certain height above the ground. It suddenly explodes into two fragments of masses m/4 and 3m/4 . An instant later, the smaller fragment is at y = + 15 cm. The larger fragment at this instant is at

(a) y = -5 cm

(b) y = +20 cm

(c) y = +5 cm

(d) y = -20 cm

Ans:- (a)

49. Scalar product also obeys

(a) Distributive law

(b) Not obey distributive law

(c) Both a and b

(d) None

Ans:- (a)

50. How much water, a pump of 2 kW can raise in one minute to a height of 10 m, take g = 10 m/s2

( a ) 1200

( b ) 100

( c ) 2000

( d ) 1000

Ans:- (a)