Quiznetik

Engineering Mechanics | Set 2

1. A screw jack used for lifting the loads is

Correct : B. a non-reversible machine

2. The potential energy stord by a spring in compression, is called strain energy.

Correct : A. Yes

3. The coefficient of restitution for inelastic bodies is

Correct : A. zero

4. Coefficient of friction is the ratio of the limiting friction to the normal reaction between the two bodies.

Correct : A. Yes

5. If a number of forces are acting at a point, their resultant will be inclined at an angle ? with the horizontal, such that

Correct : B. tan ? = ?V / ?H

6. Energy may be defined as the capacity of doing work.

Correct : A. Correct

7. The skidding away of the vehicle on a level circular path can be avoided if the force of friction between the wheels and the ground is

Correct : B. greater than

8. The moment of inertia of a solid sphere of mass m and radius r is

Correct : B. 2mr2 / 5

9. Two like parallel forces are acting at a distance of 24 mm apart and their resultant is 20 N. If the line of action of the resultant is 6 mm from any given force the two forces are

Correct : A. 15 N and 5 N

10. The range of projectile will be maximum for a given velocity of projectile, when the angle of projection (?) is

Correct : C. 45? + ?/2

11. Which of the following is a scalar quantity?

Correct : B. Speed

12. The maximum velocity of a particle moving with simple harmonic motion is

Correct : B. ?r

13. A differential pulley block has larger and smaller diameters of 100 mm and 80 mm respectively. Its velocity ratio is

Correct : B. 10

14. The coefficient of restitution for elastic bodies is one

Correct : B. Wrong

15. In ideal machines, mechanical advantage is

Correct : A. equal to

16. If the efficiency of a lifting machine is kept constant, its velocity ratio is

Correct : A. directly

17. If the resultant of a number of forces acting on a body is zero, then the body will not be in equilibrium

Correct : B. No

18. The velocity ratio for the first system of pulleys is. Where n is the number of pulleys.

Correct : C. 2n

19. The angle which the normal reaction makes with the resultant reaction is called angle of friction.

Correct : A. Agree

20. Which of the following statement is correct?

Correct : D. The kinetic energy of a body before impact is more than the kinetic energy of a body after impact.

21. If a number of coplaner forces acting at a point be in equilibrium, the sum of clockwise moments must be

Correct : A. equal to

22. An irregular body may have more than one centre of gravity.

Correct : A. Yes

23. The velocity of a particle moving with simple harmonic motion is

Correct : C. maximum

24. The polygon law of forces states that if a number of forces, acting simultaneously on a particle, be represented in magnitude and direction by the sides a polygon taken in order, then their resultant is represented in magnitude and direction by the closing side of the polygon, taken in opposite direction.

Correct : A. Correct

25. The efficiency of a lifting machine is the ratio of

Correct : D. all of the above

26. The three forces of 100 N, 200 N and 300 N have their lines of action parallel to each other but act in the opposite directions. These forces are known as

Correct : D. unlike parallel forces

27. The moment of inertia of a square of side about its diagonal is

Correct : C. a4 / 12

28. Joule is the unit of

Correct : B. work

29. In railways, the super-elevation is expressed in terms of the difference of level between the two rails.

Correct : A. True

30. The moment of a force

Correct : D. all of the above

31. The moment of inertia of a sphere of mass m and radius r, about an axis tangential to it, is

Correct : D. 7mr2 / 5

32. If three coplaner forces acting on a point are in equilibrium, then each force is proportional to the sine of the angle between the other two

Correct : A. Right

33. The centre of gravity a T-section 100 mm x 150 mm x 50 mm from its bottom is

Correct : C. 87.5 mm

34. The rate of change of momentum is directly proportional to the impressed force, and takes place in the same direction in which the force acts. This statement is known as

Correct : B. Newton's second law of motion

35. The point, through which the whole weight of the body acts, irrespective of its position, is known as

Correct : B. centre of gravity

36. The moment of inertia of a rectangular section 3cm wide and 4cm deep about X-X axis is

Correct : C. 16 cm4

37. The angle of inclination of a vehicle when moving along a circular path

Correct : B. does not depend

38. A science teacher claimed that Newton's third law of motion is involved while studying the motion of rockets. His statement is

Correct : A. justified

39. The forces, which meet at one point and their lines of action also lie on the same plane, are known as

Correct : A. coplaner concurrent forces

40. The law of motion involved in the recoil of gun is

Correct : C. Newton's third law of motion

41. The force, by which the body is attracted, towards the centre of the earth, is called

Correct : C. weight

42. The moment of inertia of a thin spherical shell of mass m and radius r, about its diameter is

Correct : B. 2mr2 / 3

43. The total time taken by a projectile to reach maximum height and to return back to the ground, is known as time of flight.

Correct : A. Yes

44. If the gravitational acceleration at any place is doubled, then the weight of a body will be

Correct : D. 2g

45. The term 'centroid' is

Correct : A. the same as centre of gravity

46. If three forces acting at a point are represented in magnitude and direction by the three sides of a triangle, taken in order, then the forces are in equilibrium

Correct : A. Yes

47. If a pendulum is taken 1 km below the earth surface in a mine, it will

Correct : A. gain

48. The ideal angle of banking provided on the curves on roads depends upon

Correct : B. (velocity)2 of the vehicle

49. The periodic time of a particle with simple harmonic motion is

Correct : B. inversely

50. The acceleration of a body sliding down an inclined surface is

Correct : A. g sin ?

51. The centre of gravity of a right angled triangle lies at its geometrical centre.

Correct : B. Incorrect

52. The moment of inertia of a solid cone of mass m and base radius r about its vertical axis is

Correct : B. 3mr2 / 10

53. The amount by which the outer edge of the rail is raised, is known as super-elevation.

Correct : A. Agree

54. The maximum efficiency of a lifting machine is

Correct : D. 1 / m x V.R.

55. Which of the following statement is correct?

Correct : D. all of the above

56. If two bodies having masses m1 and m2 (m1 > m2) have equal kinetic energies, the momentum of body having mass m1 is

Correct : C. greater than

57. The rate of doing work is known as

Correct : C. power

58. Non-coplaner concurrent forces are those forces which

Correct : A. meet at one point, but their lines of action do not lie on the same plane

59. According to principle of conservation of energy, the total momentum of a system of masses in any direction remains constant unless acted upon by an external force in that direction.

Correct : B. False

60. The total momentum of a system of masses (i.e. moving bodies) in any one direction remains constant, unless acted upon by an external force in that direction. This statement is called

Correct : D. principle of conservation of momentum

61. The unit of force in S.I. system of units of

Correct : C. newton

62. Which of the following are vector quantities?

Correct : D. all of these

63. The loss of kinetic energy during elastic impact is zero.

Correct : A. Agree

64. The centre of gravity of a triangle lies at a point where its medians intersect each other.

Correct : A. True

65. D' Alembert's principle basically depends upon Newton's second law of motion.

Correct : A. Correct

66. In order to completely specify angular displacement by a vector, it must fix

Correct : D. all of these

67. Two forces are acting at an angle of 120?. The bigger force is 40N and the resultant is perpendicular to the smaller one. The smaller force is

Correct : A. 20N

68. When a particle moves along a circular path with uniform velocity, there will be no tangential acceleration.

Correct : A. Correct

69. One joule is equal to

Correct : B. 1 N - m

70. Moment of inertia of a triangular section of base (b) and height (h) about an axis passing through its vertex and parallel to the base, is

Correct : A. nine times

71. The kinetic energy of a body

Correct : B. depends

72. A newton is defined as the force while acting upon a mass of one kg, produces an acceleration of 1 m/s2 in the direction of which it acts.

Correct : A. Yes

73. The resultant of two forces P and Q (such that P > Q) acting along the same straight line, but in opposite direction, is given by

Correct : B. P - Q

74. A framed structure is imperfect, if the number of members are

Correct : D. either (b) or (c)

75. The resultant of two equal forces P making an angle ?, is given by

Correct : B. 2 P cos ? / 2

76. The unit of mass moment of intertia in S.I. units is kg - m2

Correct : A. True

77. When a body falls freely under gravitational force, it possesses

Correct : A. no

78. The potential energy of a vertically raised body is

Correct : A. equal to

79. The moment of inertia of a square of side a about its base is a4 / 3

Correct : A. True

80. The forces which meet at one point, but their lines of action

Correct : B. do not lie

81. The amplitude is always

Correct : A. equal to

82. The static friction

Correct : D. all of the above

83. A lift moves downwards with an acceleration of 9.8 m/s2. The pressure exerted by a man on the floor of the lift is zero.

Correct : A. True

84. One kg force is equal to

Correct : C. 9.8 N

85. A force acting in the opposite direction to the motion of the body is called force of friction.

Correct : A. Agree

86. The moment of inertia of a thin disc of mass m and radius r, about an axis through its centre of gravity and perpendicular to the plane of the disc is

Correct : A. mr2 / 2

87. If the body falls freely under gravity, then the gravitational acceleration is taken as

Correct : C. Plus 9.8 m/s2

88. Mass moment of inertia of a thin rod about its one end is

Correct : D. four times

89. Newton's second law motion

Correct : A. gives

90. The principle of transmissibility of forces states that, when a force acts upon a body, its effect is

Correct : C. minimum, if it acts at the centre of gravity of the body

91. When a body of mass moment of inertia / (about a given axis) is rotated about that axis with an angular velocity ?, then the kinetic energy of rotation is

Correct : D. 0.5 I ?2

92. The unit of work in S.I. units is

Correct : D. joule

93. In a screw jcak, the effort required to lower the load is

Correct : A. less than

94. The terms 'leverage' and 'mechanical advantage' of a compound lever have got the same meaning.

Correct : A. Right

95. An ideal machine is one whose efficiency is

Correct : D. 100%

96. Tension in the cable supporting a lift is more when the lift is moving

Correct : A. upwards

97. When the lift is moving upwards with some acceleration, the pressure exerted by a man is

Correct : A. directly

98. If a body is thrown upwards, then the gravitational acceleration is taken as zero.

Correct : B. Wrong

99. The length of a second's pendulum is

Correct : B. 99.4 cm

100. Varingon's theorem of moments states that if a number of coplaner forces acting on a particle are in equilibrium, then

Correct : D. the algebraic sum of their moments about any point is equal to the moment of their resultant force about the same point