Engineering Mechanics

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

  1. newton meter
  2. watt
  3. joule
  4. kilogram meter/sec.
  5. pascal per sec.

Correct answer: (B)
watt

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

  1. newton
  2. pascal
  3. kilogram meter
  4. watt
  5. joule.

Correct answer: (E)
joule.

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

  1. kg m2
  2. m4
  3. kg/m2
  4. m3
  5. kg/m4.

Correct answer: (B)
m4

84. The units of moment of inertia of mass are

  1. kg m2
  2. m4
  3. kg/m2
  4. kg/m
  5. m2/kg.

Correct answer: (A)
kg m2

85. The weight of a body is due to

  1. centripetal force of earth
  2. gravitational pull exerted by the earth
  3. forces experienced by body in atmosphere
  4. force of attraction experienced by particles
  5. gravitational force of attraction towards the center of the earth.

Correct answer: (E)
gravitational force of attraction towards the center of the earth.

86. Two coplanar couples having equal and opposite moments

  1. balance each other
  2. produce a couple and an unbalanced force
  3. are equivalent
  4. produce a moment of couple
  5. can not balance each other.

Correct answer: (E)
can not balance each other.

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

  1. balance each other
  2. constitute a moment
  3. constitute a couple
  4. constitute a moment of couple
  5. constitute a resultant couple.

Correct answer: (E)
constitute a resultant couple.

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

  1. coplanar force
  2. non-coplanar forces
  3. lever
  4. moment
  5. couple.

Correct answer: (E)
couple.

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

  1. if any number of forces acting at a point can be represented by the sides of a polygon taken in order, then the forces are in equilibrium
  2. if any number of forces acting at a point can be represented in direction and magnitude by the sides of a polygon, then the forces are in equilibrium
  3. if a polygon representing forces acting at a point is closed then forces are in equilibrium
  4. if any number of forces acting at a point can be represented in direction and magnitude by the sides of a polygon taken in order, then the forces are in equilibrium
  5. none of the above.

Correct answer: (D)
if any number of forces acting at a point can be represented in direction and magnitude by the sides of a polygon taken in order, then the forces are in equilibrium

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

  1. Momentum and impulse
  2. Torque and energy
  3. Torque and work
  4. Kinetic energy and potential energy
  5. Moment of a force and angular momentum.

Correct answer: (E)
Moment of a force and angular momentum.

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