# Theory of machines – Section 2

11. Which of the following statement is correct?

A. The periodic time of a particle moving with simple harmonic motion is the time taken by a particle for one complete oscillation.
B. The periodic time of a particle moving with simple harmonic motion is directly proportional to its angular velocity.
C. The velocity of a particle moving with simple harmonic motion is zero at the mean position.
D. The acceleration of the particle moving with simple harmonic motion is maximum at the mean position

Correct Answer: A. The periodic time of a particle moving with simple harmonic motion is the time taken by a particle for one complete oscillation.

12. When the speed of the engine fluctuates continuously above and below the mean speed, the governor is said to be

A. stable
B. unstable
C. isochronous
D. hunt

13. When two pulleys of different diameters are connected by means of an open belt, the angle of contact at the __________ pulley must be taken into consideration.

A. smaller
B. larger

14. The maximum frictional force, which comes into play, when a body just begins to slide over the surface of the other body, is known as

A. static friction
B. dynamic friction
C. limiting friction
D. coefficient of friction

15. In a four-stroke I.C. engine, the turning moment during the compression stroke is

A. positive throughout
B. negative throughout
C. positive during the major portion of the stroke
D. negative during the major portion of the stroke

16. A body will begin to move down an inclined plane if the angle of inclination of the plane is __________ the angle of friction.

A. equal to
B. less than
C. greater than

17. The fundamental equation for correct steering is (where φ and α = Angle through which the axis of the outer wheel and inner wheel turns respectively, c = Distance between the pivots of the front axles, and d = Wheelbase) 18. The height of a Watt’s governor is

A. directly proportional to speed
B. directly proportional to (speed)2
C. inversely proportional to speed
D. inversely proportional to (speed)2

Correct Answer: D. inversely proportional to (speed)2

19. A rotor supported at A and B carries two masses as shown in the below figure. The rotor is A. dynamically balanced
B. statically balanced
C. statically and dynamically balanced
D. not balanced

Correct Answer: C. statically and dynamically balanced

20. For an isochronous Hartnell governor (where r1 and r2 = Maximum and minimum radius of rotation of balls respectively, S1 and S2 = Maximum and minimum force exerted on the sleeve respectively, and M = Mass on the sleeve) 