# Mechanical Vibrations Questions and Answers – Basic Concepts of Vibration

This set of Mechanical Vibrations Multiple Choice Questions & Answers (MCQs) focuses on “Basic Concepts of Vibration”.

1. Degrees of Freedom can be defined as number of required independent coordinates to describe a vibratory system.
a) No
b) Yes

Explanation: Degrees of freedom is must required to study any system as it gives the independent coordinates to describe the motion. The rigid body moving in space which is an unconstrained body have six degrees of freedom.

2. The number of Degrees of Freedom for following system is

a) Two
b) zero
c) one
d) infinite

Explanation: The above shown system ( diagram) has continuously distributed mass such as string stretched between two supports has infinite degrees of freedom. As such, a system is equivalent to an infinite number of masses concentrated at different points.

3. Distributed or continuous systems has
a) Finite number of degrees of freedom
b) Infinite number of degrees of freedom
c) No degrees of freedom
d) One degree of freedom

Explanation: Continuous systems like cantilever beam has an infinite number of mass points. So,infinite number of coordinates is required to specify deflected configuration .Thus cantilever beam has an infinite number of degrees of freedom.

4. Which of the following term indicates the time taken to complete one cycle?
a) Resonance
b) Time period
c) Phase period
d) Amplitude

Explanation: Time period is equal to the time for the vector to rotate through 2 Π radians. It is the time taken to complete one cycle.

5. If the motion is repeated after equal intervals of time, it is called—————- motion
a) Aperiodic motion
b) continuous motion
c) Periodic motion
d) constrained motion

Explanation: Any mechanical system gives motion when an external force applied on it. For example, motion of simple pendulum. If the motion is repeated after equal intervals of time, it can be called as periodic motion.

6. The number of Degrees of Freedom for following Beam is

a) infinite
b) two
c) finite
d) finite

Explanation: cantilever beam has an infinite number of mass points. So, infinite number of coordinates is required to specify deflected configuration .Thus cantilever beam has an infinite number of degrees of freedom.

7. Vibrations occurs in all bodies which are having mass and elasticity
a) True
b) False

Explanation: vibrations are caused due to several reasons such as presence of elastic nature of the system, external application of force. Hence the sentence is True.

8. ———–are used to protect structures from excessive forces developed in the operation of rotary machinery
a) Cushioning
b) Vibrations isolators
c) Vehicle suspension system
d) Vibration insulator

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

9. Example 1: Sea sickness when traveling on ships, boats, etc. is
Example 2: Wanted vibration is high frequency vibration probe for heart disease treatment
a) Example 1 is correct
b) Example 1 &2 are correct
c) Example 2 is correct
d) Example 1 & 2 are incorrect

Explanation: When we are on ships or boats, the excessive vibrations may cause sea sickness that vibrations are unwanted and Vibration sensors are helpful in health treatment those vibrations are wanted vibrations.

10. Note 1: Cycle, Time period, frequency, Amplitude are the basic terminologies used in study of vibrations
Note 2: Phase difference, Resonance, Damping, Periodic motion, Aperiodic motion are the basic terminologies used in study of vibrations
a) Note 1 is correct
b) Note 2 is incorrect
c) Note 1 & 2 are incorrect
d) Note 1 & 2 are correct

Explanation: Cycle, Time period, frequency, amplitude, phase difference, resonance, damping, periodic motion, aperiodic motion are the basic terminologies must be known to the study of vibrations.

11. The swinging of ball as shown in following figure is an example of vibration. What is the main reason of vibrations

a) Balanced centrifugal force in the system.
b) Unbalanced centrifugal force in the system
c) Internal excitation applied on the system
d) wind may not cause vibrations of certain system such as electricity lines, telephones, etc.

Explanation: Unbalanced centrifugal force in the system. This is caused because of non-uniform material distribution in a machine element.

Sanfoundry Global Education & Learning Series – Mechanical Vibrations.

To practice all areas of Mechanical Vibrations, here is complete set of Multiple Choice Questions and Answers.

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