This set of Machine Dynamics Multiple Choice Questions & Answers (MCQs) focuses 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
View Answer
Explanation: 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
View Answer
Explanation: 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
View Answer
Explanation: 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
View Answer
Explanation: 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%
View Answer
Explanation: 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
View Answer
Explanation: 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%
View Answer
Explanation: 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
View Answer
Explanation: Coefficient of insensitiveness is directly proportional to the friction at the sleeve and inversely proportional to the sum of masses of ball and the weight at sleeve, hence increase in friction results in increase in coefficient of insensitiveness.
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