# MCQ Questions for Class 9 Science Chapter 11 Work and Energy with Answers

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Below you will find MCQ Questions of Chapter 11 Work and Energy Class 9 Science Free PDF Download that will help you in gaining good marks in the examinations and also cracking competitive exams. These Class 9 MCQ Questions with answers will widen your skills and understand concepts in a better manner. # MCQ Questions for Class 9 Science Chapter 11 Work and Energy with answers

1. A lamp consumes 1000 J of electrical energy in 10 seconds. What is its power?

(a) 100 W

(b) 100000 W

(c) 1k W

(d) 1000 W

► (a) 100 W

2. A load of 50 kg is pulled upward by 5 m. The work done by the external force is (g = 10 m/s2)

(a) 250 J

(b) 2500 J

(c) - 250 J

(d) - 2500 J

► (b) 2500 J

3. What happens to the kinetic energy of a freely falling object which eventually stops on reaching the ground?

(a) It changes into heat & sound energy

(b) It changes into light energy

(c) It changes in potential energy

(d) None of the above

► (a) It changes into heat & sound energy

4. For what value of .ϕ. is work done maximum?

(a) 90°

(b) 0°

(c) 60°

(d) 45°

► (b) 0°

5. Work done in moving a 50 kg block through a horizontal distance of 10 m by applying a force of 100N which makes an angle of 60° with the horizontal is

(a) 200 joule

(b) 425 joule

(c) 500 joule

(d) 575 joule

► (c) 500 joule

6. A ball is dropped from a height ‘h’. The velocity of the ball when it reaches the ground is 10 m/s. Find ‘h’ (g = 10ms−2)

(a) 5.6m

(b) 12m

(c) 5m

(d) 10m

► (c) 5m

7. 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

► (c) K E. is increased to four times

8. A mass ‘m’ falls from a height ‘h’ any point on its path the total energy is:

(a) mgh/2

(b) mgh/4

(c) mgh

(d) Depends on the height

► (c) mgh

9. When you compress a coil spring you do work on it. The elastic P. E energy

(a) remains unchanged

(b) decreases

(c) disappears

(d) increase

► (d) increase

10. If 1 newton of force displaces a body by 1 m, the work done is

(a) 10 joule

(b) 5 joule

(c) 1 joule

(d) Depends on time

► (c) 1 joule

11. An object of mass 1kg has a PE of 1J relative to the ground when it is at a height of:

(a) 0.102 m

(b) 1 m

(c) 9.8 m

(d) 32 m

► (a) 0.102 m

12. 1 kWh equals

(a) 36 × 102 Joules

(b) 36 × 104 Joules

(c) 3.6 × 106 Joules

(d) None of the above

► (c) 3.6 × 106 Joules

13. If a light bulb is switched on for 20 s and it consumes 2400 J of electrical energy then it's power is

(a) 120 W

(b) 70 W

(c) 80 W

(d) 90 W

► (a) 120 W

14. Find the incorrect statement

(a) body at rest may possess energy

(b) K.E. is converted into heat and sound energy when a freely falling object eventually stops on reaching the ground

(c) the P. E of a freely falling object increases progressively

(d) there is no transfer of energy between you and the rock when you push a huge rack and fail to move it

► (c) the P. E of a freely falling object increases progressively

15. The work done on an object does not depend upon the______.

(a) displacement.

(b) force applied.

(c) the angle between force and displacement.

(d) the initial velocity of the object.

► (d) the initial velocity of the object.

16. 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

► (d) All of the above

17. 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)

► (d) both (a) and (b)

18. What is the commercial unit of energy?

(a) electron volt

(b) W/s

(c) kW h

(d) joule

► (c) kW h

19. A person A does 500 J of work in 10 minutes and another person B does 600 J of work in 20 minutes. Let the power delivered by A and B be PA and PB respectively. Then,

(a) PA = PB

(b) PA > PB

(c) PA < PB

(d) PA and PB are undefined

► (b) PA > PB

20. When the force applied and the displacement of the body are inclined at 90° with each other, then work done is

(a) Infinite

(b) Maximum

(c) Zero

(d) Unity

► (c) Zero

21. The KE. of a body in increased most by doubling its

(a) Mass

(b) Weight

(c) Speed

(d) Density

► (c) Speed

22. 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 the above

► (a) 20m

23. Newton-metre is the unit of:

(a) Power

(b) Work

(c) Momentum

(d) Gravitational intensity

► (b) Work

23. Two bodies of equal weight are kept at heights of h and 1.5 h, respectively. The ratio of their potential energies is:

(a) 3 : 2

(b) 2 : 3

(c) 1 : 1

(d) 4 : 3

► (b) 2 : 3

24. An elevator is designed to lift a load of 1000 kg through 6 floors of a building averaging 3·5 m per floor in 6 sec. Power of the elevator, neglecting other losses, will be

(a) 3·43 × 104 watt

(b) 4·33 × 104 watt

(c) 2·21 × 104 watt

(d) 5·65 × 104 watt

► (a) 3·43 × 104 watt

25. kWh is the unit of

(a) Force

(b) Power

(c) Time

(d) Energy

► (d) Energy

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

► (b) 40 J

Hope the given MCQ Questions will help you in cracking exams with good marks. These Work and Energy MCQ Questions will help you in practising more and more questions in less time.