# Dynamics of Machinery Test Questions - Set - 1

1)   Which of the following conditions should be satisfied for static balancing?

1. Dynamic forces acting on the system should be zero
2. Couple acting on the system due to dynamic force should be zero
3. Centrifugal forces acting on the system should be zero
4. Couple acting on the system due to centrifugal forces should be zero

a. Condition 1 and condition 2
b. Condition 1 and condition 3
c. Condition 3 and condition 4
d. All of the above
 Answer  Explanation  Related Ques ANSWER: Condition 1 and condition 3 Explanation: No explanation is available for this question!

2)   Which of the following factors are not responsible for unbalancing in rotating systems?

a. Errors
b. Tolerances
c. Shape of the rotor
d. None of the above
 Answer  Explanation  Related Ques ANSWER: None of the above Explanation: No explanation is available for this question!

3)   Determine magnitude of balancing mass required if 250 mm is the radius of rotation. Masses of A, B and C are 300 kg, 250 kg and 100 kg which have radii of rotation as  50 mm, 80 mm and 100 mm respectively . The angles between the consecutive masses are 110o and 270o respectively.

a. 45.36 kg
b. 47.98 kg
c. 40.50 kg
d. None of the above
 Answer  Explanation  Related Ques ANSWER: 47.98 kg Explanation: No explanation is available for this question!

4)   The unbalanced force caused due to reciprocating mass is given by the equation

a. mrω2 sin θ + mrω2 (sin 2θ/n)
b. mrω2 sin θ + mrω2 (cos 2θ/n)
c. mrω2 cos θ + mrω2 (cos 2θ/n)
d. mrω2 (sin θ + sin 2θ/n)
 Answer  Explanation  Related Ques ANSWER: mrω2 cos θ + mrω2 (cos 2θ/n) Explanation: No explanation is available for this question!

5)   Which among the following is the fundamental equation of S.H.M.?

a. x + (k / m) x =0
b. x + ω2x =0
c. x + (k/ m)2 x =0
d. x2 + ωx2 =0
 Answer  Explanation  Related Ques ANSWER: x + ω2x =0 Explanation: No explanation is available for this question!

6)   What are discrete parameter systems?

a. Systems which have infinite number of degree of freedom
b. Systems which have finite number of degree of freedom
c. Systems which have no degree of freedom
d. None of the above
 Answer  Explanation  Related Ques ANSWER: Systems which have finite number of degree of freedom Explanation: No explanation is available for this question!

7)   In which type of vibrations, amplitude of vibration goes on decreasing every cycle?

a. Damped vibrations
b. Undamped vibrations
c. Both a. and b.
d. None of the above
 Answer  Explanation  Related Ques ANSWER: Damped vibrations Explanation: No explanation is available for this question!

8)   Which of the following vibrations are classified according to magnitude of actuating force?

a. Torsional vibrations
b. Deterministic vibrations
c. Transverse vibrations
d. All of the above
 Answer  Explanation  Related Ques ANSWER: Deterministic vibrations Explanation: No explanation is available for this question!

9)   What are deterministic vibrations?

a. Vibrations caused due to known exciting force
b. Vibrations caused due to unknown exciting force
c. Vibrations which are aperiodic in nature
d. None of the above
 Answer  Explanation  Related Ques ANSWER: Vibrations caused due to known exciting force Explanation: No explanation is available for this question!

10)   According to which method, maximum kinetic energy at mean position is equal to maximum potential energy at extreme position?

a. Energy method
b. Rayleigh's method
c. Equilibrium method
d. All of the above
 Answer  Explanation  Related Ques ANSWER: Rayleigh's method Explanation: No explanation is available for this question!

11)   Which among the following is the value of static deflection (δ) for a fixed beam with central point load?

a. (Wl3) /(192 EI)
b. (Wl2) /(192 EI)
c. (Wl3) /(384 EI)
d. None of the above
 Answer  Explanation  Related Ques ANSWER: (Wl3) /(192 EI) Explanation: No explanation is available for this question!

12)   δ = (W a2b2) / (3 EIl) is the value of deflection for ______

a. simply supported beam which has central point load
b. simply supported beam which has eccentric point load
c. simply supported beam which has U.D.L. point load per unit length
d. fixed beam which has central point load
 Answer  Explanation  Related Ques ANSWER: simply supported beam which has eccentric point load Explanation: No explanation is available for this question!

13)   Determine natural frequency of a system, which has equivalent spring stiffness of 30000 N/m and mass of 20 kg?

a. 12.32 Hz
b. 4.10 Hz
c. 6.16 Hz
d. None of the above
 Answer  Explanation  Related Ques ANSWER: 6.16 Hz Explanation: No explanation is available for this question!

14)   Which formula is used to calculate mass moment of inertia (IG) of a circular rim about the axis through centre of gravity?

a. mr2/2
b. mr2/12
c. mr2/4
d. mr2
 Answer  Explanation  Related Ques ANSWER: mr2 Explanation: No explanation is available for this question!

15)   The equation m(d2x/ dt2) + c (dx/dt) + Kx = F0 sin ωt is a second order differential equation. The solution of this linear equation is given as

a. complementary function
b. particular function
c. sum of complementary and particular function
d. difference of complementary and particular function
 Answer  Explanation  Related Ques ANSWER: sum of complementary and particular function Explanation: No explanation is available for this question!

16)   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
 Answer  Explanation  Related Ques ANSWER: Angle in which displacement vector (xp) lags force vector (F0 sinωt) Explanation: No explanation is available for this question!

17)   Consider the steady-state absolute amplitude equation shown below, if ω / ωn = √2  then amplitude ratio (X/Y) =?

(X/Y) = √{1 + [ 2ξ (ω/ωn)]2} / √{[1 – (ω/ωn)2]2  + {2ξ (ω/ωn)2}

a. 0
b. 1
c. less than 1
d. greater than 1
 Answer  Explanation  Related Ques ANSWER: 1 Explanation: No explanation is available for this question!

18)   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
 Answer  Explanation  Related Ques ANSWER: amplitude of steady state vibrations and zero frequency deflection Explanation: No explanation is available for this question!

19)   Which of the following statements is/are true?

1. Magnification factor is minimum at resonance
2. The maximum value of amplification factor increases as damping factor decreases
3. The maximum value of amplification factor increases as damping factor increases
4. Magnification factor is maximum at resonance

a. Statement 1 and statement 2
b. Statements 1,2 and 3
c. Statement 2 and statement 4
d. All the above statements are true
 Answer  Explanation  Related Ques ANSWER: Statement 2 and statement 4 Explanation: No explanation is available for this question!

20)   A vertical circular disc is supported by a horizontal stepped shaft as shown below. Determine equivalent length of shaft when equivalent diameter is 20 mm. a. 1.559 m
b. 0.559 m
c. 0.633 m
d. None of the above
 Answer  Explanation  Related Ques ANSWER: 0.559 m Explanation: No explanation is available for this question!

21)   What is meant by geometric modeling?

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
 Answer  Explanation  Related Ques ANSWER: Both a. and b. Explanation: No explanation is available for this question!

22)   Simulation is a process which  _________

a. involves formation of a prototype
b. explores behavior of a model by varying input variables
c. develops geometry of an object
d. all of the above
 Answer  Explanation  Related Ques ANSWER: explores behavior of a model by varying input variables Explanation: No explanation is available for this question!

23)   In the diagram shown below, if rotor X and rotor Z rotate in same direction and rotor Y rotates in opposite direction, then specify the type of node vibration. a. Three node vibration
b. Two node vibration
c. Single node vibration
d. None of the above
 Answer  Explanation  Related Ques ANSWER: Two node vibration Explanation: No explanation is available for this question!

24)   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 behavior is observed in rotors rotating in opposite direction
d. All of the above
 Answer  Explanation  Related Ques ANSWER: Torsional vibrations do not occur in a three rotor system, if rotors rotate in same direction Explanation: No explanation is available for this question!

25)   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
 Answer  Explanation  Related Ques ANSWER: both a. and b. Explanation: No explanation is available for this question!

26)   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
 Answer  Explanation  Related Ques ANSWER: Basic condition monitoring system Explanation: No explanation is available for this question!

27)   In graph of (Transmissibility vs Frequency Ratio) shown below, the shaded region is called as____ a. Spring controlled region
b. Damping controlled region
c. Mass controlled region
d. None of the above
 Answer  Explanation  Related Ques ANSWER: Mass controlled region Explanation: No explanation is available for this question!

28)   Which of the following vibrometers have frequency ratio (ω/ωn) << 1?

a. Accelerometers
b. Velometers
c. Both a. and b.
d. None of the above
 Answer  Explanation  Related Ques ANSWER: Accelerometers Explanation: No explanation is available for this question!

29)   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
 Answer  Explanation  Related Ques ANSWER: It's natural frequency should be small Explanation: No explanation is available for this question!

30)   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
 Answer  Explanation  Related Ques ANSWER: Both a. and b. Explanation: No explanation is available for this question!

31)   Which of the following is a type of untuned vibration absorber?

a. Houdaille damper
b. Torsional vibration absorber
c. Centrifugal pendulum absorber
d. All of the above
 Answer  Explanation  Related Ques ANSWER: Houdaille damper Explanation: No explanation is available for this question!

32)   In the graph shown below, the region in which frequency ratio (ω/ωn) > √2 is known as____ a. Amplification region
b. Isolation region
c. Spring controlled region
d. None of the above
 Answer  Explanation  Related Ques ANSWER: Isolation region Explanation: No explanation is available for this question!

33)   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
 Answer  Explanation  Related Ques ANSWER: ISO – 7919-1 Explanation: No explanation is available for this question!

34)   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
 Answer  Explanation  Related Ques ANSWER: None of the above Explanation: No explanation is available for this question!