Engineering Mechanics(Engineering > Mechanical Engineering ) Questions and answers for exam Preparation

Question 1. Moment of inertia of a rectangular section having width (b) and depth (d) about an axis passing through its c.g. and parallel to the width (b), is

db³/12
bd³/12
db³/36
bd³/36

Explanation:-

Answer: Option B. -> bd³/12

Question 2. A number of forces acting at a point will be in equilibrium, if

All the forces are equally inclined
Sum of all the forces is zero
Sum of resolved parts in the vertical direction is zero (i.e. ∑V = 0)
None of these

Explanation:-

Answer: Option C. -> Sum of resolved parts in the vertical direction is zero (i.e. ∑V = 0)

Question 3. In the shown figure, if the angle of inclination of the plane is increased, then acceleration of the system will

Increase
Decrease
Remain the same
None of these

Explanation:-

Answer: Option B. -> Decrease

Question 4. 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 surfaces

Explanation:-

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

Question 5. An ideal machine is one whose efficiency is

Between 60 and 70 %
Between 70 and 80%
Between 80 and 90%
100%

Explanation:-

Answer: Option D. -> 100%

Question 6. Center of percussion is

The point of C.G.
The point of metacenter
The point of application of the resultant of all the forces tending to cause a body to rotate about a certain axis
Point of suspension

Explanation:-

Answer: Option C. -> The point of application of the resultant of all the forces tending to cause a body to rotate about a certain axis

Question 7. During elastic impact, the relative velocity of the two bodies after impact is __________ the relative velocity of the two bodies before impact.

Equal to
Equal and opposite to
Less than
Greater than

Explanation:-

Answer: Option B. -> Equal and opposite to

Question 8. Effect of a force on a body depends upon

Magnitude
Direction
Position or line of action
All of the above

Explanation:-

Answer: Option D. -> All of the above

Question 9. The velocity ratio of a differential wheel and axle with 'd' as the diameter of effort wheel and d1 and d2 as the diameters of larger and smaller axles respectively, is

D/(d₁ + d₂)
D/(d₁ - d₂)
2D/(d₁ + d₂)
2D/(d₁ - d₂)

Explanation:-

Answer: Option D. -> 2D/(d₁ - d₂)

Question 10. A lead ball with a certain velocity is made to strike a wall, it falls down, but rubber ball of same mass and with same velocity strikes the same wall, it rebounds. select the correct reason from the following:

Both the balls undergo an equal change in momentum
The change in momentum suffered by rubber ball is more than the lead ball
The change in momentum suffered by rubber ball is less than the lead ball
None of the above

Explanation:-

Answer: Option B. -> The change in momentum suffered by rubber ball is more than the lead ball