51. Least force required to draw a body up the inclined plane is W sin (plane inclination + friction angle) applied in the direction
along the plane
horizontally
vertically
at an angle equal to the angle of friction to the inclined plane
unpredictable.
Correct answer: (D) at an angle equal to the angle of friction to the inclined plane
52. Limiting force of friction is the
tangent of angle between normal-reaction and the resultant of normal reaction and limiting friction
ratio of limiting friction and normal reaction
the friction force acting when the body is just about to move
the friction force acting when the body is in motion
minimum force of friction.
Correct answer: (C) the friction force acting when the body is just about to move
53. On a ladder resting on smooth ground and leaning against vertical wall, the force of friction will be
towards the wall at its upper end
away from the wall at its upper end
upwards at its upper end
downwards at its upper end
none of the above.
Correct answer: (C) upwards at its upper end
54. On the ladder resting on the ground and leaning against a smooth vertical wall, the force of friction will be
downwards at its upper end
upwards at its upper end
perpendicular to the wall at its upper end
zero at its upper end
none of the above.
Correct answer: (D) zero at its upper end
55. Pick up the incorrect statement from the following :
The C.G. of a circle is at its center
The C.G. of a triangle is at the intersection of its medians
The C.G. of a rectangle is at the inter-section of its diagonals
The C.G. of a semicircle is at a distance of r/2 from the center
The C-G. of an ellipse is at its center.
Correct answer: (D) The C.G. of a semicircle is at a distance of r/2 from the center
56. Pick up wrong statement about friction force for dry surfaces. Friction force is
proportional to normal load between the surfaces
dependent on the materials of contact surface
proportional to velocity of sliding
independent of the area of contact surfaces
none of the above is wrong statement.
Correct answer: (C) proportional to velocity of sliding
57. Tangent of angle of friction is equal to
kinetic friction
limiting friction
angle of repose
coefficient of friction
friction force.
Correct answer: (D) coefficient of friction
58. The algebraic sum of moments of the forces forming couple about any point in their plane is
equal to the moment of the couple
constant
both of above are correct
both of above are wrong
none of the above.
Correct answer: (A) equal to the moment of the couple
59. 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
forces
independence of forces
dependence of forces
balance of force
resolution of forces.
Correct answer: (E) resolution of forces.
60. 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