Physics XI Karachi Board MCQs Chapter 7

Chapter 7 - Work, Enegrgy and Power
1. The dot product of force and displacement is __________.

(Work, Energy, Power)

2. When the force and displacement are parallel to each other, then work is __________.

(Minimum, Maximum, None of These)

3. When the force and displacement are perpendicular to each other, then work is __________.

(Minimum, Maximum, None of these)

4. When the force and displacement are in the opposite direction then the work is __________.

(Positive, Negativem, Zero)

5. The cross product of force and moment arm is __________.

(Work, Power, None of these)

6. Work is certainly done, if a body __________.

(Uses some energy, Covers some distance, Covers some displacement)

7. One electron volt is equal to __________.

(1.6 x 10-19J, 1.6 x 10-18J, 1.6 x 1019J)

8. One joule is equal to __________.

(103erg, 107erg, 10-3erg)

9. The dot product of force and velocity is called __________.

(Work, Power, Energy)

10. Power is a __________.

(Scalar Quantity, Vector Quantity, None of these)

11. Work done by a variable force is equal to __________.

(where Ddi is small, where Ddi is large, None of these)

12. A man does the work if he __________.

(Goes to fifth floor of the building, Goes to fifth floor of the building and comes back to ground floor, remains on the ground floor)

13. One horsepower is equal to __________.

(550ft.lb/s, 746 ft.lb/s, None of these)

14. Law of conservation of energy is equivalent to __________.

(Law of conservation of mass, Law of conservation of momentum, None of these)

15. The expression for the absolute potential energy of mass m at the earth surface is given as __________.

(mgh, GmMe/Re, GmMe/Re2)

16. Work done on a body is equal to __________.

(P.t, P/t, F/A2)

17. In a tug of war, team A is slowly giving way to the team B, then __________.

(Team A is doing negative work, Team A is doing positive work, team A is not doing work)

18. Kinetic energy of an object __________.

(Is independent of the direction of velocity, Depends on the direction of velocity, Is a scalar quantity)

19. Work energy equation is simply __________.

(Law of conservation of mass, Law of conservation of energy, none of these)

20. Work done by a grass cutter is maximum when he pulls it __________.

(Making an angle 45° with the floor, Making an angle of 90° with the floor, Along a line parallel to the floor)

21. A car covers some distance without any acceleration in it, then __________.

(Engine did some positive work, Engine did some negative work, none of these)

22. A body lifts a block on to a table in time Dt. The work he did, depends upon __________.

(Mass of the block, time, none of these)

23. The unit of power is __________.

(watt-hour, Joule-second, N-m/s)


24. The rate of change of momentum multiplies by displacement gives __________.

(Power, Pressure, Work)

25. A ball during its downward journey possesses __________.

(Kinetic Energy only, Potential Energy only, Both kinetic energy and potential energy)

26. Work done in the gravitational field __________.

(Is independent of the path followed, depends upon the path followed, none of these)

27. Work done in the gravitational field along a closed path is equal to __________.

(Zero, Maximum, none of these)

28. Einstein’s mass energy equation is __________.

(E = mc, E = mc2, E = m2c)

29. 1 kilowatt hour is equal to __________.

(3.6 x 106J, 6.3 x 106 J, None of these)

30. The tidal energy is due to the __________.

(Rotation of earth relative to moon, rotation of the earth around sun, none of these)

31. The dimensions of work are __________.

(ML2T-2, MLT-2, ML2T-1)

32. The dimensions of energy are __________.

(ML2T-2, MLT-2, ML2T-1)

33. The dimensions of power are __________.

(ML2T-2, ML2T-3, ML3T-2)

34. __________ of the following quantity is defined as rate expenditure of energy.

(Momentum, Power, Velocity)

35. Gravitational potential energy transform into kinetic energy if __________.

(Water evaporates, A train accelerates from rest along a horizontal track, A body falls from a table)

36. __________ of the following represents the energy lost by a 1 N weight in falling through 1 m.




(0.10 J, 1 J, 10 J)

37. Watt may be defined as __________.

(Joule per coulomb, Joule per second, Newton meter)

38. __________ of the following does not convert one type of energy into another.

(Solar cell, Steam engine, Transformer)

39. __________ of the following has the same unit as that of potential energy.

(Acceleration, Momentum, Work)

40. Experiment shows that the average power of a man walking upstairs at an ordinary pace is only about __________.

(0.22 kW, 0.33 kW, 0.55 kW)

41. A body whose mass is 40g finds that he can run up a flight of 45 steps each 16 cm high in 5.2 sec. His power is __________.

(0.44 kW, 0.54 kW, 0.64 kW)

42. A person having a mass of 60kg exerts a horizontal force of 300N in pushing a 90 kg object through a distance of 3m along a horizontal floor. The work done by this person is __________.

(7000 Joules, 900 Joules, 1100 Joules)

43. __________ is the kinetic energy of 60 g bullet moving at a speed of 600 m/s.

(10,800J, 11,800J, 12,800J)

44. A ball of mass 2kg rolls from the top of a smooth slope which is 7 m high and 14 m long to its bottom. The change in the gravitational potential energy is approximately __________.

(137J, 139J, 141J)

45. A man weighing 600 N climbs 5m vertically upward in 8 seconds his rate of working is __________.

(175watt, 275watt, 375watt)