This set of Machine Dynamics Multiple Choice Questions & Answers (MCQs) focuses on “Controlling Force”.
1. The controlling force acting on the governor is also known as ________
a) Centripetal force
b) Centrifugal force
c) Governor effort
d) Piston effort
View Answer
Explanation: When a governor rotates at a steady speed, an inward force acts on the body which is centripetal in nature. This force is called a controlling force.
2. Controlling force is in the same direction as centrifugal force.
a) True
b) False
View Answer
Explanation: When a governor rotates at a steady speed, an inward force acts on the body which is centripetal in nature. This force is called controlling force and acts in the opposite direction to that of centrifugal force.
3. If F=m.ω2.r represents the centrifugal force then which of the following expressions represents controlling force.
a) F
b) 2F
c) -2F
d) -F
View Answer
Explanation: Inward force acts on the body of the governor which is centripetal in nature. This force is called controlling force and acts in the opposite direction to that of centrifugal force.
4. Controlling force in the porter governors is due to which of the following components?
a) Spring
b) Weight of sleeve
c) Weight of governor
d) Piston effort
View Answer
Explanation: The controlling force is provided by the weight of the sleeve and balls as in Porter governor and by the spring and weight as in Hartnell governor.
5. Controlling force in the Hartnell governors is due to which of the following components?
a) Weight of balls
b) Weight of sleeve
c) Spring
d) Piston effort
View Answer
Explanation: The controlling force is provided by the weight of the sleeve and balls in case of Porter governor and by the spring and weight in case of Hartnell governor.
6. If the mass of the ball is 7.5 kg and the controlling force is 200N with an angular velocity of 100 rpm, find the radius.
a) 24 cm
b) 28 cm
c) 30 cm
d) 20 cm
View Answer
Explanation: F=m.ω2.r
200 = 7.5 (2πx100/60)2.r
Therefore r = 0.243m.
7. If the mass of the ball is 25 kg and the controlling force is 450 N with an angular velocity of 150 rpm, find the radius.
a) 7.2 cm
b) 7.9 cm
c) 8.3 cm
d) 12.3 cm
View Answer
Explanation: F = m.ω2.r
450 = 25 (2πx150/60)2.r
18 = 246.7.r
Therefore r = 0.072m.
8. Control force diagram enables to examine stability and sensitivity of the governor.
a) True
b) False
View Answer
Explanation: When the graph is drawn between the controlling force (Fc) as y-axis and radius of rotation of the balls (r) as x-axis, then the graph obtained is known as controlling force diagram of the governor. This diagram enables the stability and sensitiveness of the governor to be examined and also shows clearly the effect of friction.
9. Which of the following quantities cannot be examined from controlling force diagram?
a) Sensitivity
b) Stability
c) Effect of friction
d) Power of governor
View Answer
Explanation: The graph between the controlling force (Fc) as y-axis and radius of rotation of the balls (r) as x-axis is known as controlling force diagram. This diagram enables us to examine the stability and sensitiveness of the governor along with the effect of friction.
Sanfoundry Global Education & Learning Series – Machine Dynamics.
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