# Mechanical Vibrations Questions and Answers – Classification of Vibration

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

1. The classification of vibration depends on the number of degree of freedom necessary for their modeling
a) True
b) False

Explanation: Vibrations can be classified by degrees of freedom. It gives the number of variables required to completely describe the motion of every particle in the system.

2. The following figure shows that a massless shaft carrying a heavy disc on its end and other end is fixed. When this shaft is twisted, the vibrations produced are——————–

a) Torsional Vibrations
b) Longitudinal Vibrations
c) Transverse Vibrations
d) Continuous Vibrations

Explanation: When the shaft is untwisted or twisted , the torsional shear stresses are induced, the vibrations are called torsional vibrations.

3. Note 1: A System with finite number of degrees of freedom can be said as discrete system and a system with one degree of freedom is called a single degree of freedom system
Note 2: A System with two or more degrees of freedom is called a continues system
a) Note two is incorrect
b) Note one is incorrect
c) Note one & two are correct
d) Note one & are incorrect

Explanation: A continuous system like continuously distributed mass such as string stretched between two supports has infinite degrees of freedom. A system with one degree of freedom is called a single degree of freedom.

4. 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) Transient vibrations
b) Forced vibrations
c) Free vibrations
d) Random vibrations

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

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

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.

6. The following figure represents a ball of mass m carried on its end and other end is fixed. The vibrations caused in this are——————–

a) Longitudinal vibrations
b) Transient vibrations
c) Torsional vibrations
d) Transverse vibrations

Explanation: If mass m moves up and down parallel to the spindle axis, it is said to execute longitudinal vibrations. If it moves perpendicular to the axis of the shaft, then it is said to execute transverse vibrations.

7. If the vibrations are considered to have no source of energy dissipation, they can be said as undamped vibrations
a) No
b) Yes

Explanation: If there is no energy is dissipated in friction or lost during oscillation , the vibration is undamped vibrations.

8. The Linear differential equation is the one
a) which does not obey the law of superposition
b) which is governed by the linear vibration
c) which is not governed by the linear vibrations
d) which is governed by the non-linear vibrations

Explanation: Spring, mass and damper are the basic components of a vibratory system. If all the basic components behave linearly, the resulting vibration is known as linear vibration. They follow the law of superposition.

9. In a vibrating system, If the amount of excitation is known in magnitude, it tends to—————–
a) deterministic vibration
b) non-deterministic vibration
c) Damped vibration
d) Undamped vibration

Explanation: If the value of force or motion acting on a vibratory system is known at any time, the excitation is called deterministic. Contrary to it non-deterministic vibrations are known as random vibrations.

10. The following figure represents a ball of mass m carried on its end and other end is fixed. The vibrations produced in this are——————–

a) Transverse vibrations
b) longitudinal vibrations
c) Transient vibrations
d) Torsional vibrations

Explanation: If mass m moves perpendicular to the axis of the shaft, then it is said to execute transverse vibrations.

Sanfoundry Global Education & Learning Series – Mechanical Vibrations.

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