# Machine Dynamics Questions and Answers – Closed-Loop Transfer Function

This set of Machine Dynamics Problems focuses on “Closed-Loop Transfer Function”.

1. The initial response when the output is not equal to input is called
a) Transient response
b) Error response
c) Dynamic response
d) None of the mentioned

Explanation: Transient response of control system means changing so, this occurs mainly after two conditions and these two conditions are
1. Just after switching ‘on’ the system that means at the time of application of an input signal to the system.
2. Just after any abnormal conditions. Abnormal conditions may include sudden change in the load, short circuiting etc.

2. A control system working under unknown random actions is called
a) computer control system
b) digital data system
c) stochastic control system

Explanation: Adaptive control is the control method used by a controller which must adapt to a controlled system with parameters which vary, or are initially uncertain. Stochastic control system is a control system working under unknown random actions.

3. An automatic toaster is a __________ loop control system.
a) open
b) closed
c) partially closed
d) none of the mentioned

Explanation: The output of a toaster is not dependent on the input of the toaster. Hence, it is a open loop control system.

4. Any externally introduced signal affecting the controlled output is called a
a) feedback
b) stimulus
c) signal
d) gain control

Explanation: The instrument measuring the output of the machine for comparison with the input to the machine is known as feedback. Any externally introduced signal affecting the controlled output is called a stimulus.

5. A closed loop system is distinguished from open loop system by which of the following ?
a) Servomechanism
b) Feedback
c) Output pattern
d) Input pattern

Explanation: In open loop system we do not have any feedback but in closed loop system we have feedback.

6. ______________ is a part of the human temperature control system.
a) Digestive system
b) Perspiration system
c) Ear
d) Leg movement

Explanation: Digestive system controls the digestion of food, ear is to get the sound and leg movement is controlled by brain. So, perspiration system only controls human body temperature.

7. By which of the following the control action is determined when a man walks along a path ?
a) Brain
b) Hands
c) Legs
d) Eyes

Explanation: Walking id done through legs, so legs are only responsible.

8. _______________ is a closed loop system.
a) Auto-pilot for an aircraft
b) Direct current generator
c) Car starter
d) Electric switch

Explanation: Auto-pilot for an aircraft is a closed loop system as the input is totally dependent on the output whichever is required.

9. Which of the following devices are commonly used as error detectors in instruments ?
a) Vernistats
b) Microsyns
c) Resolvers
d) None of the mentioned

Explanation: The commonly used error detectors are self-balancing recording potentiometer, hot wire anemometer, eloctro-magnetic flow meter, torque sensor etc.

10. Which of the following should be done to make an unstable system stable ?
a) The gain of the system should be decreased
b) The gain of the system should be increased
c) The number of poles to the loop transfer function should be increased
d) The number of zeros to the loop transfer function should be increased

Explanation: By increasing the gain of the system the unstable system can be stabalized.

Sanfoundry Global Education & Learning Series – Machine Dynamics.
To practice all areas of Machine Dynamics Problems, here is complete set of 1000+ Multiple Choice Questions and Answers.

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