# Engineering Mechanics – Section 6

1. The velocity ratio of a simple wheel and axle with D and d as the diameters of effort wheel and load axle is

A. D + d
B. D – d
C. D x d
D. D / d

Correct Answer: D. D / d

2. The unit of force in S.I. system of units is

A. dyne
B. kilogram
C. Newton
D. Watt

3. The moment of inertia of a solid cone of mass m and base radius r about its vertical axis is

A. 3mr2/5
B. 3mr2/10
C. 2mr2/5
D. 4mr2/5

4. A body is said to move or vibrate with simple harmonic motion if its acceleration is directed towards the mean position.

A. True
B. False

5. A ladder is resting on a rough ground and leaning against a smooth vertical wall. The force of friction will act

A. downward at its upper end
B. upward at its upper end
C. zero at its upper end
D. perpendicular to the wall at its upper end

Correct Answer: C. zero at its upper end

6. Joule is the unit of

A. force
B. work
C. power
D. velocity

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

A. W sin θ
B. W cos θ
C. W sec θ
D. W cosec θ

Correct Answer: D. W cosec θ

8. A spherical body is symmetrical about its perpendicular axis. According to Routh’s rule, the moment of inertia of a body about an axis passing through its center of gravity is(where, M = Mass of the body and S = Sum of the squares of the two semi-axes.)

A.MS/3
B.MS/4
C.MS/5
D.none of these

9. The three forces of 100 N, 200 N and 300 N have their lines of action parallel to each other but act in the opposite directions. These forces are known as

A. coplanar concurrent forces
B. coplanar non-concurrent forces
C. like parallel forces
D. unlike parallel forces

Correct Answer: D. unlike parallel forces

10. The efficiency of a lifting machine is the ratio of

A. output to the input
B. work done by the machine to the work done on the machine
C. mechanical advantage to the velocity ratio
D. all of the above

Correct Answer: D. all of the above