# Work & Energy (VSA)

1. Seema tried to push a heavy rock of 100 kg for 200 s but could not move it. Find the work done by Seema at the end of 200 s. [2017 (T-II)]

2. At what speed a body of mass 1 kg will have a kinetic energy of 1 J? [2011 (T-II)]

3. Define 1 Joule of work. [2017 (T-II)]

4. Identify the energy possessed by a rolling stone. [2017 (T-II)]

5. Identify the kind of energy possessed by a running athlete. [2017 (T-II)]

6. What would be the amount of work done on an object by a force, if the displacement of the object is zero? [2017 (T-II)]

7. How much work is done by a weight lifter when he holds a weight of 80 kgs on his shoulders for two minutes? [2017 (T-II)]

8. A car and a truck are moving with the same velocity of 60 km/hr. Which one has more kinetic energy? (Mass of truck > Mass of car). [2017 (T-II)]

9. A body is thrown vertically upwards. Its velocity goes on decreasing. Write the change in kinetic energy when its velocity becomes zero. [2017 (T-II)]

10. A force of 10 N moves a body with a constant speed of 2 m/s. Calculate the power of the body. [2017 (T-II)]

11. What will be the kinetic energy of a body when its mass is made four times and the velocity is doubled? [2017 (T-II)]

12. A freely falling object eventually stops on reaching the ground. What happens to its kinetic energy on reaching the ground? [2017 (T-II)]

13. State the energy conversions in a dry cell. [2017 (T-II)]

14. What is the work done by the Earth in moving around the Sun? [2017 (T-II)]

15. A coolie is walking on a railway platform with a load of 30 kg on his head. How much work is done by coolie?

16. How many times does the kinetic energy of a body become when its speed is doubled? [2017 (T-II)]

17. In an oscillating pendulum, at what positions the potential and kinetic energy are maximum? [2017 (T-II)]

18. Define S.I. unit of work? [2017 (T-II)]

19. Name the type of energy possessed by a raised hammer? [2017 (T-II)]

20. What is the form of energy possessed by a running car? [2017 (T-II)]

21. State the value of commercial unit of electrical energy in joules? [2017 (T-II)]

22. A 2 m high person is holding a 25 kg trunk on his head and is standing at a roadways bus-terminus. How much work is done by the person? [2017 (T-II)]

23. A horse of mass 210 kg and a dog of mass 25 kg are running at the same speed. Which of the two possesses more kinetic energy? How? [2017 (T-II)]

24. If the speed of the body is halved, what is the change in its kinetic energy? [2017 (T-II)]

25. Moon is experiencing a gravitational force due to Earth and is revolving around the Earth in a circular orbit. How much work is done by moon? [2017 (T-II)]

26. Give the formula for calculating work done. What is the SI unit of work? [2017 (T-II)]

27. Define 1 watt of power. [2017 (T-II)]

28. A man holding a bucket of water on his head stands stationary. Is he doing any work? Give reason. [2017 (T-II)]

29. Name the type of energy possessed by the following? [2017 (T-II)]

(i) Stretched slinky (ii) Speeding car

30. Write the formula to measure the work done, if the displacement of the object is at an angle of 90° to the direction of force. [2017 (T-II)]

31. If we lift a body of mass 70 g vertically upwards 10 m then calculate the force required to lift the body (g = 10 ms–2). [2017 (T-II)]

32. At what rate is electrical energy consumed by a bulb of 60 watt? [2017 (T-II)]

33. Give an example of a body having potential energy due to change of shape. [2017 (T-II)]

34. When is work done by a force zero? [2017 (T-II)]

35. If the heart works 60 joules in one minute, what is its power? [2017 (T-II)]

36. Name the term used for the sum of kinetic energy and potential energy of a body. [2017 (T-II)]

37. Write the observed energy transformation that takes place at thermal power station. [2017 (T-II)]

38. A 40 kg girl is running along a circular path of radius 1 m with a uniform speed. How much work is done by the girl in completing one circle? [2017 (T-II)]

39. Calculate the work done when a force of 15 N moves a body by 5 m in its direction. [2017 (T-II)]

40. Write the S.I. unit of power. [2017 (T-II)]

41. A student is writing a three hours science paper. How much work is done by student? Give reasons to your answer. [2017 (T-II)]

42. When displacement is in a direction opposite to the direction of force applied, what is the type of work done? [2017 (T-II)]

43. What is the work done against gravity when a body is moved horizontally along a frictionless surface? [2017 (T-II)]

OTHER IMPORTANT QUESTION

1. When does a force do work? How is this work measured?

2. State the mathematical expression for work.

3. What are the conditions for doing work?

4. Is work a scalar or a vector quantity?

5. Give one example of a moving body, where no work is done.

6. Explain, why no work is done when a man pushes a wall.

7. Define the term ‘power’.

8. A boy climbs 100 stairs to reach at the top of a building. What happens to the potential energy of the boy?

9. Water flows down the mountains to the plains. What happens to the potential energy of water?

10. Give two examples in which a body possesses potential energy.

11. What do you understand by the term kinetic energy?

12. What determines the kinetic energy of a body of a given mass?

13. What is the biggest source of energy?

14. How is power related to work and time?

15. What do you understand by the term mechanical energy?

16. What do you understand by the term potential energy?

17. State the law of conservation of energy.

18. What do you understand by the term energy transformation?

19. What kind of energy transformation takes place when the hands are rubbed?

CBSE Class 9 Science

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