## Class 9 Science Objective Chapter – 11 Work, Power and Energy

Here we are providing Class 9 Science Objective Chapter – 11 Work, Power and Energy because its very important for Class 9 students as we all know that every board exam question has MCQs so that students should practice these questions so that students can get good marks in board. Class 9 Science Objective Chapter – 11 Work, Power and Energy is an extremely important and its also a year in which students learn the fundamentals of concepts that help them lay a solid foundation for their higher education. Here we are providing in Class Class 9 Science Objective Chapter – 11 Work, Power and Energy 100+ questions  so that students practice more and more. If you want class wise Notes Then Click Here

Class 9 Science Objective Chapter – 11 Work, Power and Energy

1. Work done by centripetal force is

( A ) > 0

( B )  0

( C ) < 0

( D ) 0

Ans – ( D )

2.An iron sphere of mass 10 kg has the same diameter as an aluminium sphere of mass is 3.5 kg. Both spheres are dropped simultaneously from a tower. When they are lo m above the ground, they have the same.

( A ) acceleration

( B ) momenta

( C ) potential energy

( D ) kinetic energy

Ans – ( A )

3.A car is accelerated on a levelled road and attains a velocity 4 times of its initial velocity. In this process the potential energy of the car

( A ) does not change

( B ) becomes twice to that of initial

( C ) becomes 4 times that of initial

( D ) becomes 16 times that of initial

Ans – ( A )

4. When a body falls freely towards the earth, then its total energy

( A ) Decreases

( B ) Increases

( C ) First increases and then decreases

( D ) Remains constant

Ans – ( D )

5.In case of negative work the angle between the force and displacement is (NCERT Exemplar)

( A ) 0°

( B ) 45°

( C ) 90°

( D ) 180°

Ans – ( D )

6. If work is done at a faster rate, then

( A ) power is more

( B ) No power is required to do work

( C ) power is less

( D ) Infinite power is required

Ans – ( A )

7.An iron sphere of mass 10 kg has the same diameter as an aluminium sphere of mass is 3.5 kg. Both spheres are dropped simultaneously from a tower. When they are lo m above the ground, they have the same.

( A ) acceleration

( B ) momenta

( C ) potential energy

( D ) kinetic energy

Ans – ( A )

8. Moon revolves around the earth due to gravitational force (F) of earth on moon. The work done by the gravitational force is (r = radius of circular orbit of moon)

( A ) F.2πr

( B ) F.πr

( C ) zero

( D ) negative work

Ans – ( C )

9.An iron sphere of mass 10 kg has the same diameter as an aluminium sphere of mass is 3.5 kg. Both spheres are dropped simultaneously from a tower. When they are 10 m above the ground, they have the same

( A ) acceleration

( B ) momenta

( C ) potential energy

( D ) kinetic energy

Ans – ( A )

10.A girl is carrying a school bag of 3 kg mass on her back and moves 200 m on a levelled road. The work done against the gravitational force will be (g = 10 ms²)

( A ) 6 × 10³ J

( B ) 6 J

( C ) 0.6 J

( D ) zero

Ans – ( D )

11. Work done by a body is

( A ) negative, positive or zero

( B ) always positive

( C ) always zero

( D ) always negative

Ans – ( A )

12.A girl is carrying a school bag of 3 kg mass on her back and moves 200 m on a levelled road. The work done against the gravitational force will be (g =10 m s’2)

( A ) 6×103 J

( B ) 6 J

( C ) 0.6 J

( D ) zero

Ans – ( D )

13.Which one of the following is not the unit of energy?

( A ) joule

( B ) newton metre

( C ) kilowatt

( D ) kilowatt hour

Ans – ( C )

14. 1 W. S = ________?

( A ) 10 joule

( B ) 1 joule

( C ) 3.6 × 106 joule

( D ) 2 joule

Ans – ( B )

15.When a body falls freely towards the earth, then its total energy

( A ) increases

( B ) decreases

( C ) remains constant

( D ) first increases and then decreases

Ans – ( C )

16.The work done on an object does not depend upon the

( A ) displacement

( B ) force applied

( C ) angle between force and displacement

( D ) initial velocity of the object

Ans – ( D )

17. Scientifically, work is said to be done in which of the following cases

( A ) Manish pulls the trolley for a certain distance

( B ) Mira studies for her exam

( C ) Manoj pushes the wall with no change in the position of wall

( D ) Mira pulls the wall with no change in the position of wall

Ans – ( A )

18.A car is accelerated on a levelled road and attains a velocity 4 times of its initial velocity. In this process the potential energy of the car

( A ) does not change

( B ) becomes twice to that of initial

( C ) becomes 4 times that of initial

( D ) becomes 16 times that of initial

Ans – ( A )

19.Water stored in a dam possesses

( A ) no energy

( B ) electrical energy

( C ) kinetic energy

( D ) potential energy

Ans – ( D )

20. P.E of a spring increases when it is in the state of

( A ) compression

( B ) neither a nor b

( C ) expansion

( D ) both a and b

Ans – ( D )

21.The number of joules contained in 1 kWh is

( A ) 36 × 105 J

( B ) 3.6 × 107 J

( C ) 36 × 108 J

( D ) 3.7 × 107 J

Ans – ( A )

22. When speed of the moving object is doubled its

( A ) Acceleration is doubled

( B ) Momentum becomes four times more

( C ) K E. is increased to four times

( D ) Potential energy is increased

Ans – ( C )

23.Two army persons A and B each of weight of 500 N climb up a rope through a height of 10 m. A takes 20 s while B takes 40 s to achieve this task. What is ratio of the powers of person A and B?

( A ) 1 : 2

( B ) 1 : 4

( C ) 2 : 1

( D ) 14 : 1

Ans – ( C )

24. A ball is thrown vertically upwards. Its velocity keeps on decreasing. What happens to its kinetic energy when its reaches the maximum height?

( A ) Kinetic energy is double

( B ) Kinetic energy is zero

( C ) Kinetic energy is maximum at maximum height

( D ) Kinetic energy is half of initial value

Ans – ( B )

25.If speed of a car becomes 2 times, its kinetic energy becomes

( A ) 4 times

( B ) 8 times

( C ) 16 times

( D ) 12 times

Ans – ( A )

26. A stone weighing 1 kg is dropped from rest from a height of 4 metres above the ground. When it has free-fallen 1 metre its total energy with respect to the ground is

( A ) 15 J

( B ) 40 J

( C ) 20 J

( D ) 30 J

Ans – ( B )

27.Work done by friction

( A ) increases kinetic energy of body

( B ) decreases kinetic energy of body

( C ) increases potential energy of body

( D ) decreases potential energy of body.

Ans – ( B )

28. The energy possessed by an oscillating pendulum of a clock is

( A ) kinetic energy

( B ) potential energy

( C ) restoring energy

( D ) mechanical energy

Ans – ( D )

29.When a coil spring is compressed, the work is done on the spring. The elastic potential energy

( A ) increases

( B ) decreases

( C ) disappears

( D ) remains unchanged

Ans – ( A )

30. What is the commercial unit of energy?

( A ) electron volt

( B ) W/s

( C ) kW h

( D ) joule

Ans – ( C )

31.One joule work is said to be done when

( A ) a force of 1 N displaces a body by 1 cm

( B ) a force of 1 N displaces a body by 1 m

( C ) a force of 1 dyne displaces a body by 1 m

( D ) a force of 1 dyne displaces a body by 1 cm.

Ans – ( B )

32. Calculate the work done in moving a body of mass 50 Kg through a height of 5 m.(g = 10m/s2)​

( A ) 250 J

( B ) 2500 J

( C ) 25 x 103 J

( D ) 2.5 x 105 J

Ans – ( B )

33.SI unit of power is

( A ) watt

( B ) joule

( C ) newton

( D ) metre

Ans – ( A )

34. Find the correct statement

( A ) 1 Gigawatt is equal to 109W

( B ) power is the rate of doing work

( C ) both a and b

( D ) none of these

Ans – ( D )

35.Mechanical energy of a body includes

( A ) kinetic energy only

( B ) potential energy only

( C ) kinetic energy and potential energy

( D ) none of these

Ans – ( C )

36. If a force of F newton moves a body with constant speed v, the power delivered by it is

( A ) F/v

( B ) Fv

( C ) F2v

( D ) v/F

Ans – ( B )

37.Commercial unit of energy is

( A ) joule

( B ) kWh

( C ) watt

( D ) newton

Ans – ( B )

38. According to the law of conservation of energy

( A ) Energy can’t be destroyed

( B ) Energy can’t be created

( C ) Energy can be transformed from one from to another

( D ) All of the above

Ans – ( D )

39.Potential energy of a body depends on its

( A ) position

( B ) configuration

( C ) position and configuration

( D ) mass and velocity

Ans – ( C )

40. In SI system, the unit of P.E. is

( A ) erg

( B ) dyne-cm

( C ) J

( D ) None of these

Ans – ( C )

41.If speed of a car becomes 2 times, its kinetic energy becomes

( A ) 4 times

( B ) 8 times

( C ) 16 times

( D ) 12 times

Ans – ( A )

42. In the SI system, the unit of potential energy is

( A ) newton

( B ) joule

( C ) watt

( D ) metre per second

Ans – ( B )

43. When a body like earth is moving in a circular path the work done in that case is zero because:

( A ) Centripetal force acts in the direction of motion of the body

( B ) Centripetal force acts along the radius of circular path

( C ) Gravitational force acts along the radius of circular path

( D ) Centrifugal force acts perpendicular to the radius of circular path

Ans – ( B )

44. Two bodies of equal weight are kept at heights of h and 1.5 A, respectively. The ratio of their PE is

( A ) 3 : 2

( B ) 2 : 3

( C ) 1 : 1

( D ) 4 : 3

Ans – ( B )

45. A car is accelerated on a leveled road and attains a velocity 4 times of its initial velocity. In this process, the kinetic energy of the car

( A ) Becomes twice to that of the initial

( B ) Becomes four times to that of the initial

( C ) Remains the same

( D ) Becomes 16 times to that of the initial

Ans – ( D )

46.  On tripling the speed of motion of a body, the change in K.E. is

( A ) 9 times

( B ) 8 times

( C ) 4 times

( D ) 2 times

Ans – ( A )

47. The type of energy possessed by a simple pendulum, when it is at the mean position is:

( A ) Kinetic energy

( B ) Potential energy

( C ) Kinetic + Potential energy

( D ) Sound energy

Ans – ( A )

48. A stone is tied to a string and whirled in a circular path. The work done by the stone is :

( A ) negative

( B ) zero

( C ) positive

( D ) none of the above

Ans – ( B )

49. A man is carrying the heavy luggage from one platform to the other of a Railway station but still according to the logics of science his work done is said to be zero. Can you opt out the correct reason?

( A ) The force is acting along the direction of displacement of luggage

( B ) The force is acting perpendicular to the direction of displacement of luggage

( C ) The force is acting opposite to the direction of displacement of luggage

( D ) None of these

Ans – ( B )

50. 9800 joule of energy was spent to raise a mass of 50kg, the mass was raised to a height of

( A ) 20m

( B ) 980m

( C ) 10m

( D ) none of these

Ans – ( A )

51. What is the energy possessed by an object due to its motion?

( A ) Potential energy

( B ) Electrical energy

( C ) Kinetic energy

( D ) None of them

Ans – ( C )

52. The linear momentum of a body of mass 2kg is 16kgms−1. What is its K. E?

( A ) 64J

( B ) 70J

( C ) 60J

( D ) none of these

Ans – ( A )

53. The capacity of a body to perform work is called:

( A ) Energy

( B ) Work

( C ) Power

( D ) Heat

Ans – ( A )

54. Potential energy and kinetic energy are types of

( A ) Electrical energy

( B ) Magnetic energy

( C ) Thermal energy

( D ) Mechanical energy

Ans – ( D )

55. The rate of work done is called:

( A ) Energy

( B ) Power

( C ) Capacity

( D ) All of these

Ans – ( B )

56. A body of mass 5 kg is moving with an acceleration of 5 ms-2 gets a displacement of 2m, the work done by the force is:​

( A ) 75 J

( B ) 25 J

( C ) 100 J

( D ) 50 J

Ans – ( D )

57. The capacity to perform work is obtained from :

( A ) Food

( B ) Energy

( C ) Power

( D ) All of these

Ans – ( B )

58. Work done is said to be positive when a force causes displacement:

( A ) In its own direction

( B ) In the direction opposite to the applied force

( C ) In the direction at right angles to the direction of applied force

( D ) None of the above

Ans – ( A )

59. Which of the following does not possess the ability to do work not because of motion ?

( A ) a sparrow flying in the sky

( B ) a sparrow moving slowly on the ground

( C ) a sparrow in the nest on a tree

( D ) a squirrel going up a tree

Ans – ( C )

60. Two masses m and 2m are dropped from certain height ‘h’. Then on reaching the ground,

( A ) K.E. of them will be equal

( B ) K.E. of the heavier is 4 times the K.E. of the lighter

( C ) K.E. of the lighter is 4 times the K.E. of the heavier

( D ) K.E. of the heavier is more than that of the lighter

Ans – ( D )

61. The momentum of a bullet of mass 20 g fired from a gun is 10 kg m/s. The kinetic energy of this bullet in kJ will be:

( A ) 25

( B ) 2.5

( C ) 0.25

( D ) 5

Ans – ( B )

62. A rocket rises up in the air due to the force generated by the fuel. The work done by the:

( A ) fuel is negative work and that of force of gravity is positive work

( B ) fuel is positive work and that of force of gravity is negative work

( C ) both fuel and force of gravity do positive work

( D ) both fuel and force of gravity do negative work

Ans – ( B )

63. If a man hold an object of mass 20 kg at 1.3 m then the value of work done will be

( A ) 26 J

( B ) 30 J

( C ) 20 J

Ans – ( D )

64. A body is moved through a distance of 3 m in the following different ways. In which case is the maximum work done?

( A ) when pushed over an inclined plane

( B ) when lifted vertically upward

( C ) when pushed over smooth rollers

( D ) when pushed on a plain horizontal surface

Ans – ( B )

65. Which of the following is a source of energy?

( A ) Sun

( B ) Nuclear reactions

( C ) Tides

( D ) All of the above

Ans – ( D )