# Dynamics of Machinery 3

Mechanical Engineering MCQ Question Papers: DRDO, ISRO, Interview

Subject: Dynamics of Machinery 3

Part 3: List for questions and answers of Dynamics of Machinery

Q1. What is the range of audible sound pressure to which a human ear can be subjected to?
a) 10^-5 n/m^2 to 10-12 n/m^2
b) 10^-12 w/m^2 to 10 w/m^2
c) 2 x 10^-5 n/m^2 to 200 n/m^2
d) 2 x 10^-5 n/m^2 to 300 n/m^2

Q2. Sound wave has a frequency of 8 khz at 22o c. Determine its wavelength.
a) 0.043 m
b) 0.039 m
c) 0.125 m
d) 0.0125 m

Q3. Determine velocity of sound in air at 50o (for air, γ = 1.4)
a) 1002.5 m/s
b) 360.45 m/s
c) 350 m/s
d) None of the above

Q4. What is meant by reverberant chamber?
a) Chambers having walls, ceiling and flooring acoustically reflected
b) Chambers having walls, ceiling and flooring covered by sound absorbing materials
c) Chambers having walls and ceiling made of different absorbing material
d) None of the above

Q5. Which of the following absorptive treatment can be used to cover the interior of a box to prevent the reverberant sound?
a) Open cell foam
b) Glass fiber mat
c) Both a. And b.
d) None of the above

Q6. Which type of earplugs contains silicon rubber and a fixing agent?
a) Semi insert protectors
b) Custom moulded earplugs
c) Pre-fabricated earplugs
d) Canal caps

Q7. Which of the following construction equipments have highest noise level?
a) Compressors
b) Generators
c) Pneumatic wrenches
d) Pumps

Q8. The noise level generated by domestic air conditioner ranges between _________
a) 38 db to 70 db
b) 35 db to 52 db
c) 62 db to 88 db
d) 50 db to 60 db

Q9. Which among the following is not considered when reference standards are used in the field of mechanical vibration and shock, monitoring and analysis of machines?
a) Terminology
b) Methods of testing
c) Methods of measurement
d) None of the above

Q10. Which basic document describes general requirements for measurement and evaluation of machine vibrations using shaft measurements?
a) Iso – 10816-1
b) Iso – 7919-1
c) Both a. And b.
d) None of the above

Q11. Which of the following is a type of unturned vibration absorber?
a) damper
b) Torsional vibration absorber
c) Centrifugal pendulum absorber
d) All of the above

Q12. Which of the following methods can be used to reduce excitation level at the source?
a) Lubrication of joints
b) Balancing inertia forces
c) Both a. And b.
d) None of the above

Q13. Which of the following conditions is/are to be satisfied by the seismometer for it to be used as velometer?
a) It’s natural frequency should be large
b) It’s natural frequency should be small
c) It’s output signal should be proportional to relative acceleration of the vibrating
body
d) None of the above

Q14. Which type of monitoring system uses stroboscope to measure speed of the machine?
a) Portable condition monitoring system
b) Basic condition monitoring system
c) Computer based condition monitoring system
d) None of the above

Q15. Seismometer can be used to measure acceleration of any instrument only if _____
a) It’s natural frequency is high
b) It generates output signal which is proportional to relative acceleration of the
vibrating object
c) Both a. And b.
d) None of the above

Q16. Which of the following statements is/are true?
a) Torsional vibrations do not occur in a three rotor system, if rotors rotate in same
direction
b) Shaft vibrates with maximum frequency when rotors rotate in same direction
c) Zero node behaviour is observed in rotors rotating in opposite direction
d) All of the above

Q17. What is meant by geometric modelling?
a) Representation of an object with graphical information
b) Representation of an object with non-graphical information
c) Both a. And b.
d) None of the above

Q18. Magnification factor is the ratio of ______
a) Zero frequency deflection and amplitude of steady state vibrations
b) Amplitude of steady state vibrations and zero frequency deflection
c) Amplitude of unsteady state vibrations and zero frequency distribution
d) None of the above

Q19. What is meant by phase difference or phase angle in forced vibrations?
a) Difference between displacement vector (xp) and velocity vector vp
b) Angle in which displacement vector leads force vector by (f0 sinωt)
c) Angle in which displacement vector (xp) lags force vector (f0 sinωt)
d) None of the above

Q20. Simulation is a process which _________
a) Involves formation of a prototype
b) Explores behaviour of a model by varying input variables
c) Develops geometry of an object
d) All of the above

Part 3: List for questions and answers of Dynamics of Machinery