Mechanical Engineering Multiple Choice Questions

140 TOP MOST ENGINEERING MECHANICS – Mechanical Engineering Multiple Choice Questions and Answers

140 TOP MOST ENGINEERING MECHANICS – Mechanical Engineering Multiple Choice Questions and Answers

Engineering Mechanics Interview Questions and Answers pdf

1. The unit of force in S.I. units is

2. The unit of work or energy in S.I. units is

3. The unit of power in S.I. units is

4. Forces are called concurrent when their lines of action meet in

5. Forces are called coplanar when all of them acting on body lie in

6. A force acting on a body may

7. Which is the correct statement about law of polygon of forces ?

8. Effect of a force on a body depends upon

9. If a number of forces act simultaneously on a particle, it is possible

11. A force is completely defined when we specify

12. If two equal forces of magnitude P act at an angle 9°, their resultant will be

13. The algebraic sum of the resolved parts of a number of forces in a given direction is equal to the resolved part of their resultant in the same direction. This is as per the principle of

14. The resolved part of the resultant of two forces inclined at an angle 9 in a given direction is equal to

15. Which of the following do not have identical dimensions ?

16. Which of the following is not the unit of distance ?

17. Which of the following is not the unit of power ?

18. Which of the following is not the unit of work, energy and heat ?

19. Which of the following is not the unit of pressure ?

20. The weight of a body is due to

21. The forces, which meet at one point, but their lines of action do not lie in a plane, are called

22. When trying to turn a key into a lock, following is applied

23. Which of the following is not a scalar quantity

24. According to principle of transmissibility of forces, the effect of a force upon a body is

25. Which of the following is a vector quantity

26. The magnitude of two forces, which when acting at right angle produce resultant force of VlOkg and when acting at 60° produce resultant of Vl3 kg. These forces are

27. A number of forces acting at a point will be in equilibrium if

28. Two non-collinear parallel equal forces acting in opposite direction

29. According to principle of moments

30. Which of the following is not a vector quantity

31. According to law of triangle of forces

33. If a rigid body is in equilibrium under the action of three forces, then

34. D’ Alembert’s principle is used for

35. A heavy ladder resting on floor and against a vertical wall may not be in equilibrium, if

38. According to Lami’s theorem

39. Two coplanar couples having equal and opposite moments

40. A framed structure is perfect if it contains members equal to

42. The product of either force of couple with the arm of the couple is called

43. In detennining stresses in frames by methods of sections, the frame is divided into two parts by an imaginary section drawn in such a way as not to cut more than

44. The center of gravity of a uniform lamina lies at

45. Center of gravity of a solid cone lies on the axis at the height

46. Center of percussion is

47. Center of gravity of a thin hollow cone lies on the axis at a height of

48. The units of moment of inertia of an area are

49. The center of percussion of the homogeneous rod of length L suspended at the top will be

50. The center of gravity of a triangle lies at the point of

51. The units of moment of inertia of mass are
(a) kg m2
(b) m4
(c) kg/m2
(d) kg/m
(e) m2/kg.
Ans: a

52. The possible loading in various members of framed structures are
(a) compression or tension
(b) buckling or shear
(c) shear or tension
(d) all of the above
(e) bending.
Ans: a

53. A heavy string attached at two ends at same horizontal level and when central dip is very small approaches the following curve
(a) catenary
(b) parabola
(c) hyperbola
(d) elliptical
(e) circular arc.
Ans: b

54. A trolley wire weighs 1.2 kg per meter length. The ends of the wire are attached to two poles 20 meters apart. If the horizontal tension is 1500 kg find the dip in the middle of the span
(a) 2.5 cm
(b) 3.0 cm
(c) 4.0 cm
(d) 5.0 cm
(e) 2.0 cm.
Ans: c

55. From a circular plate of diameter 6 cm is cut out a circle whose diameter is a radius of the plate. Find the e.g. of the remainder from the center of circular plate
(a) 0.5 cm
(b) 1.0 cm
(c) 1.5 cm
(d) 2.5 cm
(e) 0.25 cm.
Ans: a

56. Pick up the incorrect statement from the following :
(a) The C.G. of a circle is at its center
(b) The C.G. of a triangle is at the intersection of its medians
(c) The C.G. of a rectangle is at the inter-section of its diagonals
(d) The C.G. of a semicircle is at a distance of r/2 from the center
(e) The C-G. of an ellipse is at its center.
Ans: d

57. The center of percussion of a solid cylinder of radius r resting on a horizontal plane will be
(a) r/2
(b) 2r/3
(c) r/A
(d) 3r/2
(e) 3r/A.
Ans: d

61. In the equation of virtual work, following force is neglected
(a) reaction of any smooth surface with which the body is in contact
(b) reaction of a rough surface of a body which rolls on it without slipping
(c) reaction at a point or an axis, fixed in space, around which a body is con-strained to turn
(d) all of the above
(e) none of the above.
Ans: d

62. If a suspended body is struck at the center of percussion, then the pressure on die axis passing through the point of suspension will be
(a) maximum
(b) minimum
(c) zero
(d) infinity
(e) same as the force applied.
Ans: c

65. The resultant of the following three couples 20 kg force, 0.5 m arm, $ ve sense 30 kg force, 1 m arm, – ve sense 40 kg force, 0.25 m arm, + ve sense having arm of 0.5 m will be
(a) 20 kg, – ve sense
(b) 20 kg, + ve sense
(c) 10 kg, + ve sense
(d) 10 kg, – ve sense
(e) 45 kg, + ve sense.
Ans: a

68. Angle of friction is the
(a) angle between normal reaction and the resultant of normal reaction and the limiting friction
(b) ratio of limiting friction and normal reaction
(c) the ratio of minimum friction force to the friction force acting when the body is just about to move
(d) the ratio of minimum friction force to friction force acting when the body is in motion
(e) ratio of static and dynamic friction.
Ans: a

69. The coefficient of friction depends on
(a) area of contact
(b) shape of surfaces
(c) strength of surfaces
(d) nature of surface
(e) all of the above.
Ans: d

70. Least force required to draw a body up the inclined plane is W sin (plane inclination + friction angle) applied in the direction
(a) along the plane
(b) horizontally
(c) vertically
(d) at an angle equal to the angle of friction to the inclined plane
(e) unpredictable.
Ans: d

71. The ratio of limiting friction and normal reaction is known as
(a) coefficient of friction
(b) angle of friction
(c) angle of repose
(d) sliding friction
(e) friction resistance.
Ans: a

72. Which one of the following statements is not correct
(a) the tangent of the angle of friction is equal to coefficient of friction
(b) the angle of repose is equal to angle of friction
(c) the tangent of the angle of repose is equal to coefficient of friction
(d) the sine of the angle of repose is equal to coefficient to friction
(e) none of the above.
Ans: d

73. On a ladder resting on smooth ground and leaning against vertical wall, the force of friction will be
(a) towards the wall at its upper end
(b) away from the wall at its upper end
(c) upwards at its upper end
(d) downwards at its upper end
(e) none of the above.
Ans: c

74. On the ladder resting on the ground and leaning against a smooth vertical wall, the force of friction will be
(a) downwards at its upper end
(b) upwards at its upper end
(c) perpendicular to the wall at its upper end
(d) zero at its upper end
(e) none of the above.
Ans: d

76. Frictional force encountered after commencement of motion is called
(a) post friction
(b) limiting friction
(c) kinematic friction
(d) frictional resistance
(e) dynamic friction.
Ans: e

77. Coefficient of friction is the
(a) angle between normal reaction and the resultant of normal reaction and the limiting friction
(b) ratio of limiting friction and normal reaction
(c) the friction force acting when the body is just about to move
(d) the friction force acting when the body is in motion
(e) tangent of angle of repose.
Ans: b

78. Pick up wrong statement about friction force for dry surfaces. Friction force is
(a) proportional to normal load between the surfaces
(b) dependent on the materials of contact surface
(c) proportional to velocity of sliding
(d) independent of the area of contact surfaces
(e) none of the above is wrong statement.
Ans: c

79. A body of weight W on inclined plane of a being pulled up by a horizontal force P will be on the point of motion up the plane when P is equal to
(a) W
(b) W sin (a + $)
(c) Wtan(a + <|))
(d) Wan(a-<t>)
(e) Wtana.
Ans: c

80. A particle moves along a straight line such that distance (x) traversed in t seconds is given by x = t2 (t – 4), the acceleration of the particle will be given by the equation
(a) 3t2-lt
(b) 3t2+2t
(c) 6f-8
(d) 6f-4
(e) 6t2-8t.
Ans: c

81. If rain is falling in the opposite direction of the movement of a pedestrain, he has to hold his umbrella
(a) more inclined when moving
(b) less inclined when moving
(c) more inclined when standing
(d) less inclined when standing
(e) none of the above.
Ans: d

86. A projectile is fired at an angle 9 to the vertical. Its horizontal range will be maximum when 9 is
(a) 0°
(b) 30°
(c) 45°
(d) 60°
(e) 90°.
Ans: c

88. Limiting force of friction is the
(a) tangent of angle between normal-reaction and the resultant of normal reaction and limiting friction
(b) ratio of limiting friction and normal reaction
(c) the friction force acting when the body is just about to move
(d) the friction force acting when the body is in motion
(e) minimum force of friction.
Ans: c

89. Coulomb friction is the friction between
(a) bodies having relative motion
(b) two dry surfaces
(c) two lubricated surfaces
(d) solids and liquids
(e) electrically charged particles.
Ans: a

90. Dynamic friction as compared to static friction is
(a) same
(b) more
(c) less
(d) may be less of more depending on nature of surfaces and velocity
(e) has no correlation.
Ans: c

91. Tangent of angle of friction is equal to
(a) kinetic friction
(b) limiting friction
(c) angle of repose
(d) coefficient of friction
(e) friction force.
Ans: d

92. Kinetic friction is the
(a) tangent of angle between normal reaction and the resultant of normal reaction and the limiting friction
(b) ratio of limiting friction and normal reaction
(c) the friction force acting when the body is just about to move
(d) the friction force acting when the body is in motion
(e) dynamic friction.
Ans: d

95. The effort required to lift a load W on a screw jack with helix angle a and angle of friction <j) is equal to
(a) Wtan(a + <)>)
(b) Wtan(a-<)>)
(c) Wcos(a + <t>)
(d) Wsin(a + <(>)
(e) W (sin a + cos <j>).
Ans: a

96. A semi-circular disc rests on a horizontal surface with its top flat surface horizontal and circular portion touching down. The coefficient of friction between semi-cricular disc and horizontal surface is i. This disc is to be pulled by a horizontal force applied at one edge and it always remains horizontal. When the disc is about to start moving, its top horizontal force will
(a) remain horizontal
(b) slant up towards direction of pull
(c) slant down towards direction of pull
(d) unpredictable
(e) none of the above.
Ans: c

97. A particle inside a hollow sphere of radius r, having coefficient of friction -rr can rest upto height of
(a) r/2
(b) r/A
(c) r/%
(d) 0.134 r
(e) 3r/8.
Ans: d

98. The algebraic sum of moments of the forces forming couple about any point in their plane is
(a) equal to the moment of the couple
(b) constant
(c) both of above are correct
(d) both of above are wrong
(e) none of the above.
Ans: a

99. A single force and a couple acting in the
same plane upon a rigid body
(a) balance each other
(b) cannot balance each other
(c) produce moment of a couple
(d) are equivalent
(e) none of the above.
Ans: b

100. If three forces acting in one plane upon a rigid body, keep it in equilibrium, then they must either
(a) meet in a point
(b) be all parallel
(c) at least two of them must meet
(d) all the above are correct
(e) none of the above.
Ans: d

101. The maximum frictional force which comes into play when a body just begins to slide over another surface is called
(a) limiting friction
(b) sliding friction
(c) rolling friction
(d) kinematic friction
(e) dynamic friction.
Ans: a

102. The co-efficient of friction depends upon
(a) nature of surfaces
(b), area of contact
(c) shape of the surfaces
(d) ail of the above.
(e) (a) and (b) above.
Ans: a

104. The necessary condition for forces to be in equilibrium is that these should be
(a) coplanar
(b) meet at one point ;
(c) both (a) and (b) above
(d) all be equal
(e) something else.
Ans: c

105. If three forces acting in different planes can be represented by a triangle, these will be in
(a) non-equilibrium
(b) partial equilibrium
(c) full equilibrium
(d) unpredictable
(e) none of the above.
Ans: a

106. If n = number of members andy = number of joints, then for a perfect frame, n =
(a) j-2
(b) 2j-l
(c) 2/-3
(d) 3/-2
(e) 2/ -4.
Ans: c

107. A body moves, from rest with a constant acceleration of 5 m per sec. The distance covered in 5 sec is most nearly
(a) 38 m
(b) 62.5 m
(C) 96 m
(d) 124 m
(e) 240 m.
Ans: b

108. A flywheel on a motor goes from rest to 1000 rpm in 6 sec. The number of revolutions made is nearly equal to
(a) 25
(b) 50
(c) 100
(d) 250
(e) 500.
Ans: b

109. Which of the following is the locus of a point that moves in such a manner that its distance from a fixed point is equal to its distance from a fixed line multiplied by a constant greater than one
(a) ellipse
(b) hyperbola
(c) parabola
(d) circle
(e) none of the above.
Ans: b

111. Which of the following is not the unit of energy
(a) kg m
(b) kcal
(c) wattr
(d) watt hours
(e) kg m x (m/sec)2.
Ans: c

112. A sample of metal weighs 219 gms in air, 180 gms in water, 120 gms in an unknown fluid. Then which is correct statement about density of metal
(a) density of metal can’t be determined
(b) metal is twice as dense as water
(c) metal will float in water
(d) metal is twice as dense as unknown fluid
(e) none of the above.
Ans: a

113. The C.G. of a solid hemisphere lies on the central radius 3r
(a) at distance — from the plane base 3r
(b) at distance — from the plane base 3r
(c) at distance — from the plane base 3r
(d) at distance — from the plane base or
(e) at distance — from the plane base.
Ans: d

117. The C.G. of a plane lamina will not be at its geometrical centre in the case of a
(a) right angled triangle
(b) equilateral triangle
(c) square
(d) circle
(e) rectangle.
Ans: a

119. The C.G. of a right circular solid cone of height h lies at the following distance from the base
(a) h/2
(b) J/3
(c) h/6
(d) h/4
(e) 3/i/5.
Ans: d

122. The M.I. of hollow circular section about a central axis perpendicular to section as compared to its M.I. about horizontal axis is
(a) same
(b) double
(c) half
(d) four times
(e) one fourth.
Ans: b

126. Which of the following is the example of lever of first order
(a) arm of man
(b) pair of scissors
(c) pair of clinical tongs
(d) all of the above
(e) none of the above.
Ans: d

127. A pair of smith’s tongs is an example of the lever of
(a) zeioth order
(b) first order
(c) second order
(d) third order
(e) fourth order.
Ans: c

128. In the lever of third order, load W, effort P and fulcrum F are oriented as follows
(a) W between P and F
(b) F between W and P
(c) P between W and F
(d) W, P and F all on one side
(e) none of the above.
Ans: a

129. The angle which an inclined plane makes with the horizontal when a body placed on it is about to move down is known as angle of
(a) friction
(b) limiting friction
(c) repose
(d) kinematic friction
(e) static friction.
Ans: c

130. In actual machines
(a) mechanical advantage is greater than velocity ratio
(b) mechanical advantage is equal to velocity ratio
(c) mechanical advantage is less than velocity ratio
(d) mechanical advantage is unity
(e) none of the above.
Ans: c

131. In ideal machines
(a) mechanical advantage is greater than velocity ratio
(b) mechanical advantage is equal to velocity ratio
(c) mechanical advantage is less than velocity ratio
(d) mechanical advantage is unity
(e) none of the above.
Ans: b

136. A cable with a uniformly distributed load per horizontal meter run will take the following shape
(a) straight line
(b) parabola
(c) hyperbola
(d) elliptical
(e) part of a circle.
Ans: b

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