91. 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
92. 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
93. Kinetic friction is the
(a) tangent of angle between normal reac-tion and the resultant of normal reac-tion 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
94. A cable with a uniformly distributed load per horizontal metre run will take the following shape
(a) straight line
(b) parabola
(c) hyperbola
(d) elliptical
(e) part of a circle.
Ans: b
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
103. 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
104. 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
(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
92. 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
93. Kinetic friction is the
(a) tangent of angle between normal reac-tion and the resultant of normal reac-tion 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
94. A cable with a uniformly distributed load per horizontal metre run will take the following shape
(a) straight line
(b) parabola
(c) hyperbola
(d) elliptical
(e) part of a circle.
Ans: b
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
103. 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
104. 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
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