# Mechanical Vibrations MCQ (Multiple Choice Questions)

1. Why is the study of vibrations strongly recommended?
a) to stop the mechanical systems
b) to stop the structural systems
c) to help the mechanical systems to vibrate more
d) to identify the result of Oscillations of any structural or mechanical system

Explanation: Vibration is a result of Oscillatory motion of any structural or mechanical system is strongly recommended to identify the result of vibration on above systems, which also helps to identify the wear of any mechanical systems.

2. What is used to protect structures from excessive forces developed in the operation of rotary machinery?
a) Vibration insulator
b) Vehicle suspension system
c) Vibrations isolators
d) Cushioning

Explanation: Vibration isolators are used in structures to prevent transfer of vibrations from systems. It isolates an object.

3. If the vibrations are initiated by an initial energy present in the system and no other
source is present, the resulting vibrations are called?
a) Free vibrations
b) Random vibrations
c) Transient vibrations
d) Forced vibrations

Explanation: If any system vibrates on its own after an initial disturbance, It can be said as free vibration.

a) Oscillations arise in the machines such as diesel engines
b) Oscillation of simple pendulum
c) Electric bells
d) Machine tools

Explanation: The vibrations produced by the external force applied on system are forced vibrations such as electric bells, Machine tool, etc. Simple pendulum vibrates on its own after initial disturbance.

5. Which of the following method is used to derive the equation of motion of a vibratory system?
a) Finite element method
b) Approximation method
c) Rayleigh’ s method
d) Summation method

Explanation: Rayleigh’ s method, Energy method, Equilibrium method are the methods used in analysis of vibrations to derive the equation of motion.

6. Which is the correct sequence for vibration analysis?
a) Mathematical Modeling, Derivation of Governing Equation, Solution to the Governing Equation, Interpretation of Results
b) Mathematical Modeling, Interpretation of Results, Solution to the Governing Equation, Derivation of Governing Equation
c) Interpretation of Results, Solution to the Governing Equation, Derivation of Governing Equation, Mathematical Modeling
d) Derivation of Governing Equations, Mathematical Modeling, Interpretation of Results, Solution to the Governing equation

Explanation: Mathematical modeling is the first step to start the procedure of vibration analysis as it gives the basic behavior of all components. Based on mathematical modeling one can derive the governing equation to describe the vibrations of system. After that solution for governing equation is obtained and final results are made.

7. When do the viscous damping occurs in a mechanical system?
a) when the system is in contact with another mechanical system
b) when the system is in contact with a viscous liquid
c) when the system is in contact with a non viscous liquid
d) when the system is in contact with a solid material

Explanation: Viscous damping is added to mechanical system as a means of vibration control. It occurs in mechanical system, when it is contact with viscous liquid.

8. Which of the following is an example of a simple harmonic motion ?
a) x1 = A1 sec ωt
b) x1 = A1 cosec ωt
c) x1 = A1 cos ωt
d) x1 = A1 tan ωt

Explanation: Harmonic motion is represented in terms of circular cosine and sine function. The motion gives by x1 = A1 cos ωt is an example of a simple harmonic motion.

9. Rayleigh’s Energy method is based on which principle?
a) Principle of conservation of mass
b) Principle of conservation of momentum
c) Principle of energy distortion
d) Principle of conservation of energy

Explanation: In a real dynamic system, the energy consisted is both Kinetic and Potential. So, the total energy must remain constant. T + U = Constant. This signifies the principle of conservation of energy.

10. Find the value of angular velocity (rad/s) of damped vibration when angular velocity of natural vibration is 30 rad/s and the damping factor is 0.3.
a) 28.61
b) 30.21
c) 42.21
d) 30

Explanation: By formula we have, ωd= ωn×$$\sqrt{1-ζ^2}$$

Now replacing the values of angular velocity of natural vibration (ωn) as 30 rad/s and the damping factor as 0.3 in the above formula, we have ωd=28.61 rad/s.

11. When does resonance occur?
a) The external excitation has a lower frequency as that of the natural frequency of the system
b) The external excitation has zero frequency
c) The external excitation has the same frequency as that of the natural frequency of the system
d) The external excitation has a higher frequency as that of the natural frequency of the system

Explanation: Resonance occurs when the external excitation has the same frequency as that of the natural frequency of the system, leading to a large displacement of the amplitude from the mean position.

12. Which is used to protect passengers from uncomfortable situation when moving over rough land?
a) Vehicle lubrication system
b) Vehicle cooling system
c) Vehicle pumping system
d) Vehicle suspension system

Explanation: Vehicle suspension system is used to prevent the road shocks from being transmitted
to the vehicle components.

## Chapterwise Multiple Choice Questions on Mechanical Vibrations

Our MCQs focus on all topics of the Mechanical Vibrations subject, covering all topics. This will help you to prepare for exams, contests, online tests, quizzes, viva-voce, interviews, and certifications. You can practice these MCQs chapter by chapter starting from the 1st chapter or you can jump to any chapter of your choice.

## 1. MCQ on Fundamentals of Mechanical Vibrations

The section contains multiple choice questions and answers on the importance of the study of vibration, basic concepts of vibration, classification of vibration, vibration analysis procedure, spring elements, mass or inertia elements, damping elements, harmonic motion, and harmonic analysis.

## 2. Free Vibration of Single Degree of Freedom Systems

The section covers Mechanical Vibrations questions and answers on single degree of freedom system vibrations, including undamped translational and torsional systems, Rayleigh’s Energy Method, and vibrations with viscous damping.

## 3. Harmonically Excited Vibrations

The section contains MCQs on harmonically excited vibrations.

If you would like to learn "Mechanical Vibrations" thoroughly, you should attempt to work on the complete set of 1000+ MCQs - multiple choice questions and answers mentioned above. It will immensely help anyone trying to crack an exam or an interview.

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