Engineering Mechanics MCQs

Question 1

According to Lami’s theorem

Accepted Answer

If the three forces acting at a point are in equilibrium, then each force is proportional to the sine of the angle between the other two

Answer

The three forces must be equal

Answer

The three forces must be at 120° to each other

Answer

The three forces must be in equilibrium

Question 2

According to principle of moments

Accepted Answer

If a system of coplanar forces is in equilibrium, then the algebraic sum of their moments about any point in their plane is zero

Answer

If a system of coplanar forces is in equilibrium, then their algebraic sum is zero

Answer

The algebraic sum of the moments of any two forces about any point is equal to moment of the resultant about the same point

Answer

Positive and negative couples can be balanced

Question 3

The velocity of a body on reaching the ground from a height h, is

Accepted Answer

$$\sqrt {2{	ext{gh}}} $$

Answer

$$2\sqrt {{	ext{gh}}} $$

Answer

$$\sqrt {{	ext{gh}}} $$

Answer

$$2{	ext{g}}\sqrt {	ext{h}} $$

Question 4

The force induced in the string AB due to the load W, as shown in the below figure is

Accepted Answer

W cosecθ

Answer

W sinθ

Answer

W cosθ

Answer

W secθ

Question 5

An ideal machine is one whose efficiency is

Accepted Answer

100%

Answer

Between 60 and 70 %

Answer

Between 70 and 80%

Answer

Between 80 and 90%

Question 6

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

Accepted Answer

The floor and wall both are smooth surfaces

Answer

The floor is smooth, the wall is rough

Answer

The floor is rough, the wall is smooth

Answer

The floor and wall both are rough surfaces

Question 7

In the equation of virtual work, following force is neglected

Accepted Answer

All of the above

Answer

Reaction of any smooth surface with which the body is in contact

Answer

Reaction of a rough surface of a body which rolls on it without slipping

Answer

Reaction at a point or an axis, fixed in space, around which a body is constrained to turn

Question 8

The equivalent length of a simple pendulum which gives the same frequency as compound pendulum is

Accepted Answer

$$\frac{{{	ext{k}}_{	ext{G}}^2 + {{	ext{h}}^2}}}{{	ext{h}}}$$

Answer

$$\frac{{	ext{h}}}{{{	ext{k}}_{	ext{G}}^2 + {{	ext{h}}^2}}}$$

Answer

$$\frac{{{{	ext{h}}^2}}}{{{	ext{k}}_{	ext{G}}^2 + {{	ext{h}}^2}}}$$

Answer

$$\frac{{{	ext{k}}_{	ext{G}}^2 + {{	ext{h}}^2}}}{{{{	ext{h}}^2}}}$$

Question 9

When the lift is moving upwards with some acceleration, the pressure exerted by a man is __________ to its acceleration.

Accepted Answer

Directly proportional

Answer

Inversely proportional

Answer

Cube root

Answer

None of these