Machine Dynamics Multiple Choice Questions on “Coefficient of Insensitiveness”.
1. When the speed of the governor decreases, which of the following effect does friction causes?
a) Prevents downward movement of sleeve
b) Prevents downward movement of sleeve
c) Prevents radial outward movement of balls
d) Increases downward movement of sleeve
Answer: a
Clarification: In actual conditions there is always friction acting at joints and operating mechanisms of the governor, because of this while slowing down friction prevents the downward movement of sleeve.
2. Because of friction acting at the joints, while speeding up it prevents the downward movement of sleeve.
a) True
b) False
Answer: b
Clarification: In actual conditions there is always friction acting at joints and operating mechanisms of the governor, because of this while speeding up friction prevents the upward movement of sleeve.
3. When the speed of the governor increases, which of the following effect does friction causes?
a) Prevents downward movement of sleeve
b) Prevents downward movement of sleeve
c) Prevents radial inward movement of balls
d) Increases upward movement of sleeve
Answer: b
Clarification: In actual conditions there is always friction acting at joints and operating mechanisms of the governor, as a consequence when the speed of rotation increases.
4. For a porter governor, the following data is given:
Mass of each ball = 3kg
Mass on the sleeve = 15Kg
Length of each arm = 20cm
Ball path at life = 12 cm
Path at maximum speed = 16 cm
Calculate range of speed.
a) 14.15 rpm
b) 28.3 rpm
c) 56.9 rpm
d) 32.4 rpm
Answer: b
Clarification: h1 = 0.16m
h2 = 0.12m
N12 = ((m+M)/m) x895/h1= (18÷3)x895/0.16 = 33563
N1 = 183.2 rpm
N22 = ((m+M)/m) x895/h2= (18÷3)x895/0.12 = 44750
N2 = 211.5 rpm
therefore range = 28.3 rpm.
5. For a porter governor, the following data is given:
Mass of each ball = 3kg
Mass on the sleeve = 15Kg
Length of each arm = 20cm
Ball path at life = 12 cm
Path at maximum speed = 16 cm, If there is a friction at the sleeve of 10 N, find the coefficient of insensitiveness.
a) 11.3%
b) 5.00%
c) 8.66%
d) 5.66%
Answer: d
Clarification: We know that coefficient of insensitiveness is given by
F/(m+M)g
= 10/(3 + 15)9.81 = 5.66%.
6. For a porter governor, the following data is given:
Mass of each ball = 5kg
Mass on the sleeve = 20Kg
Length of each arm = 20cm
Ball path at life = 12 cm
Path at maximum speed = 16 cm
Calculate range of speed in rpm.
a) 25.9
b) 51.8
c) 12.9
d) 31.2
Answer: a
Clarification: h1 = 0.16m
h2 = 0.12m
N12 = ((m+M)/m) x895/h1= (25÷5)x895/0.16 = 27968
N1 = 167.2 rpm
N22 = ((m+M)/m) x895/h2= (25÷5)x895/0.12 = 37291
N2 = 193.1 rpm
therefore range = 25.9 rpm.
7. For a porter governor, the following data is given:
Mass of each ball = 5kg
Mass on the sleeve = 20Kg
Length of each arm = 20cm
Ball path at life = 12 cm
Path at maximum speed = 16 cm, If there is a friction at the sleeve of 10 N, find the coefficient of insensitiveness.
a) 4%
b) 6%
c) 5%
d) 7%
Answer: a
Clarification: We know that coefficient of insensitiveness is given by
F/(m+M)g
= 10/(5 + 20)9.81 = 4%.
8. With increase in friction, coefficient of insensitiveness increases.
a) True
b) False