Questions and answers for exam Preparation

MCQs

Total Questions : 735 | Page 6 of 74 pages

Question 51. 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

Discuss Question

Answer: Option A. -> equal to the moment of the couple

Question 52. 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

friction
limiting friction
repose
kinematic friction

Discuss Question

Answer: Option C. -> repose

Question 53. A force acting on a body may

introduce internal stresses
retard its motion
change its motion
all of the above.

Discuss Question

Answer: Option D. -> all of the above.

Question 54. Which is the correct statement about law of polygon of forces ?

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
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
if a polygon representing forces acting at a point is closed then forces are in equilibrium
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

Discuss Question

Answer: Option 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

Question 55. When trying to turn a key into a lock, following is applied

coplanar force
non-coplanar forces
moment
couple

Discuss Question

Answer: Option D. -> couple

Question 56. The effort required to lift a load W on a screw jack with helix angle a and angle of friction

Wtan(a + )
Wtan(a-)
Wcos(a + )
Wsin(a + )

Discuss Question

Answer: Option A. -> Wtan(a + )

Question 57. In actual machines

mechanical advantage is greater than velocity ratio
mechanical advantage is equal to velocity ratio
mechanical advantage is less than velocity ratio
mechanical advantage is unity

Discuss Question

Answer: Option C. -> mechanical advantage is less than velocity ratio

Question 58. A heavy ladder resting on floor and against a vertical wall may not be in equilibrium, if

the floor is smooth, the wall is rough
the floor is rough, the wall is smooth
the floor and wall both are smooth surfaces
the floor and wall both are rough sur-faces

Discuss Question

Answer: Option C. -> the floor and wall both are smooth surfaces

Question 59. The C.G. of a right circular solid cone of height h lies at the following distance from the base

Discuss Question

Answer: Option D. -> h/4

Question 60. According to principle of moments

if a system of coplanar forces is in equilibrium, then their algebraic sum is zero
if a system of coplanar forces is in equilibrium, then the algebraic sum of their moments about any point in their plane is zero
the algebraic sum of the moments of any two forces about any point is equal to moment of theiwesultant about the same point
positive and negative couples can be balanced

Discuss Question

Answer: Option B. -> if a system of coplanar forces is in equilibrium, then the algebraic sum of their moments about any point in their plane is zero