Engineering Questions with Answers - Multiple Choice Questions

# Machine Dynamics MCQ – Governors

1 - Question

The height of a Watt’s governor (in metres) in equal to
a) 8.95/N2
b) 89.5/N2
c) 895/N2
d) 8950/N2

Explanation: Height of a Watt governor = g/ω2
= 9.81/(2πN/60)2
= 895/N2
where N = Speed of the arm and ball about the spindle axis.

2 - Question

The ratio of the height of a Porter governor (when the length of arms and links are equal) to the height of a Watt’s governor is
a) m/m+M
b) M/m+M
c) m + M/m
d) m + M/M

Explanation: Mass of the central load (M) increases the height of governor in the ratio m + M/m
where m = Mass of the ball, and
M = Mass of the load on the sleeve.

3 - Question

When the sleeve of a Porter governor moves upwards, the governor speed
a) increases
b) decreases
c) remains unaffected

Explanation: When the loaded sleeve moves up and down the spindle, the frictional force acts on it in a direction opposite to that of the motion of sleeve. The + sign is used when the sleeve moves upwards or the governor speed increases and negative sign is used when the sleeve moves downwards or the governor speed decreases.

4 - Question

A Hartnell governor is a
a) pendulum type governor
d) inertia governor

Explanation: Since in hartnell governor spring is used, therefore it is the spring loaded governor.

5 - Question

Which of the following governor is used to drive a gramophone ?
a) Watt governor
b) Porter governor
c) Pickering governor
d) Hartnell governor

Explanation: A Pickering governor is mostly used for driving gramophone. It consists of three straight leaf springs arranged at equal angular intervals round the spindle. Each spring carries a weight at the centre. The weights move outwards and the springs bend as they rotate about the spindle axis with increasing speed.

6 - Question

Which of the following is a spring controlled governor?
a) Hartnell
b) Hartung
c) Pickering
d) all of the mentioned

Explanation: None

7 - Question

For two governors A and B, the lift of sleeve of governor A is more than that of governor B, for a given fractional change in speed. It indicates that
a) governor A is more sensitive than governor B
b) governor B is more sensitive than governor A
c) both governors A and B are equally sensitive
d) none of the mentioned

Explanation: The greater the lift of the sleeve corresponding to a given fractional change in speed, the greater is the sensitiveness of the governor. It may also be stated in another way that for a given lift of the sleeve, the sensitiveness of the governor increases as the speed range decreases.

8 - Question

The sensitiveness of a governor is given by
a) ωmean/ω2 – ω1
b) ω2 – ω1/ ωmean
c) ω2 – ω1/ 2ωmean
d) none of the mentioned

Explanation: Let N1 = Minimum equilibrium speed,
N2 = Maximum equilibrium speed, and
N = Mean equilibrium speed = N1 + N2 / 2
Sensitiveness of the governor = N1 – N2 / 2
= 2(N1 + N2) / N1 + N2
= ω2 – ω1/ ωmean
where ω1 and ω2 = Minimum and maximum angular speed, and
ωmean = Mean angular speed.

9 - Question

In a Hartnell governor, if a spring of greater stiffness is used, then the governor will be
a) more sensitive
b) less sensitive
c) isochronous
d) none of the mentioned

Explanation: Stiffness is directly proportional to sensitiveness. Therefore, it stifness is greater, the governor will be less sensitive.

10 - Question

A governor is said to be hunting, if the speed of the engine
a) remains constant at the mean speed
b) is above the mean speed
c) is below the mean speed
d) fluctuates continuously above and below the mean speed

Explanation: A governor is said to be hunt if the speed of the engine fluctuates continuously above and below the mean speed. This is caused by a too sensitive governor which changes the fuel supply by a large amount when a small change in the speed of rotation takes place.

11 - Question

A hunting governor is
a) more stable
b) less sensitive
c) more sensitive
d) none of the mentioned

Explanation: None

12 - Question

Isochronism in a governor is desirable when
a) the engine operates at low speeds
b) the engine operates at high speeds
c) the engine operates at variable speeds
d) one speed is desired under one load

Explanation: The isochronous governor is not of practical use because the sleeve will move to one of its extreme positions immediately the speed deviates from the isochronous speed.

13 - Question

The power of a governor is equal to
a) (c2/1 + 2c )(m + M) h
b) (2c2/1 + 2c )(m + M) h
c) (3c2/1 + 2c )(m + M) h
d) (4c2/1 + 2c )(m + M) h

Explanation: None

14 - Question

When the relation between the controlling force (FC) and radius of rotation (r) for a spring controlled governor is FC = a.r + b, then the governor will be
a) stable
b) unstable
c) isochronous
d) none of the mentioned

Explanation: For the governor to be stable, the controlling force (FC) must increase as the radius of rotation (r) increases, i.e. FC / r must increase as r increases.

15 - Question

For a governor, if FC is the controlling force, r is the radius of rotation of the balls, the stability of the governor will be ensured when
a) dFC /dr > FC/r
b) dFC /dr < FC /r
c) dFC /dr = 0
d) none of the mentioned