Dynamics of Machinery multiple Choice Questions
1. A microphone that uses the piezoelectric effect
A. Dynamic
B. Condenser
C. Crystal
D. Carbon
Answer:
C.Crystal
2. It describes the output of a microphone over a range of frequencies.
A. Directivity
B. Sensitivity
C. Frequency response
D. All of the above
Answer:
C.Frequency response
3. The most important terms that are used to describe the sound field around asound emitting object
A. Far , Near Field
B. Free ,Diffuse Field
C. A and B both
D. None of the above
Answer:
C.A and B both
4. The sound waves behave in a much more complex fashion, and there is no fixedrelationship between ________________.
A. Sound pressure
B. pressure and distance
C. Sound energy
D. Sound intensity
Answer:
B.pressure and distance
5. The sound far field is beginning at a distance of ____________ .
A. pressure and distance
B. Sound energy
C. Sound pressure
D. 2 wavelengths away from the sound source
Answer:
D.2 wavelengths away from the sound source
6. The resonant frequency of a mass-spring system depends upon ________
A. stiffness
B. surface density
C. depth of air space
D. all of the above
Answer:
D.all of the above
7. Calculate equivalent stiffness of the spring for the system shown below,which has spring stiffness of 3000 N/m
A. 1000 N/m
B. 2250 N/m
C. 2000 N/m
D. None of the above
Answer:
B.2250 N/m
8. Which of the following is incorrect regarding inertia force?
A. Imaginary force
B. Acts upon a rigid body
C. Brings the body to equilibrium
D. Same direction as of accelerating force
Answer:
D.Same direction as of accelerating force
9. D-Alembert’s principle is used for which of the following?
A. Change static problem into a dynamic problem
B. Change dynamic problem to static problem
C. To calculate moment of inertia of rigid bodies
D. To calculate angular momentum of a system of masses
Answer:
B.Change dynamic problem to static problem
10. Determine logarithmic decrement, if the amplitude of a vibrating bodyreduces to 1/6th in two cycles.
A. 0.223
B. 0.8958
C. 0.389
D. None of the above
Answer:
B.0.8958
11. Calculate logarithmic decrement if damping factor is 0.33.
A. 1.36
B. 3.23
C. 5.16
D. 2.19
Answer:
D.2.19
12. In damped free vibrations, which parameters indicate vibrations?
A. Natural frequency
B. Rate of decay of amplitude
C. Both a. and b.
D. None of the above
Answer:
B.Rate of decay of amplitude
13. What is meant by critical damping coefficient?
A. Frequency of damped free vibrations is less than zero
B. The motion is aperiodic in nature
C. Both a. and b.
D. None of the above
Answer:
B.The motion is aperiodic in nature
14. Which of the following relations is true for viscous damping?
A. Force α relative displacement
B. Force α relative velocity
C. Force α (1 / relative velocity)
D. None of the above
Answer:
B.Force α relative velocity
15. Which among the following is the value of static deflection (δ) for a fixedbeam with central point load?
A. (Wl3) /(192 EI)
B. (Wl2) /(192 EI)
C. (Wl3) /(384 EI)
D. None of the above
Answer:
A.(Wl3) /(192 EI)
16. According to which method, maximum kinetic energy at mean position isequal to maximum potential energy at extreme position?
A. Energy method
B. Rayleigh’s method
C. Equilibrium method
D. All of the above
Answer:
B.Rayleigh’s method
17. The motion of a system executing harmonic motion with one naturalfrequency is known as _______
A. principal mode of vibration
B. natural mode of vibration
C. both a. and b.
D. none of the above
Answer:
C.both a. and b.
18. Fluid resistance causes damping which is known as ______
A. Resistance damping
B. Fluid damping
C. Viscous damping
D. Liquid damping
Answer:
C.Viscous damping
19. In which direction does the accelerating force acts?
A. Opposite to the motion
B. Along the motion
C. Perpendicular to motion
D. Variable
Answer:
B.Along the motion
20. The time interval after which the motion is repeated itself is known as ___________ .
A. Time period
B. Cycle
C. Frequency
D. Isolation
Answer:
A.Time period
21. Frequency of vibrations is usually expressed in
A. Number of cycles per hour
B. Number of cycles per minute
C. Number of cycles per second
D. None of these
Answer:
C.Number of cycles per second
22. The motion completed during one time period is known as _______.
A. Period of vibration
B. Cycle
C. Frequency
D. All of the above
Answer:
B.Cycle
23. Which of the following is a type of free vibration?
A. Longitudinal vibrations
B. Transverse vibrations
C. Torsional vibrations
D. A, B and C
Answer:
D.A, B and C
24. In a spring-mass system, which of the following force is not considered?
A. Spring force
B. Damping force
C. Accelerating force
D. A and B
Answer:
B.Damping force
Free Vibration
25. What is meant by node point?
A. The point at which amplitude of vibration is maximum
B. The point at which amplitude of vibration is minimum
C. The point at which amplitude of vibration is zero
D. None of the above
Answer:
C.The point at which amplitude of vibration is zero
26. The periodic time is given by _______.
A. ω / 2 π
B. 2 π / ω
C. 2 π × ω
D. π/ω
Answer:
B.2 π / ω
27. The velocity of a particle moving with simple harmonic motion is _______ atthe mean position.
A. Zero
B. Minimum
C. Maximum
D. None of the mentioned
Answer:
C.Maximum
28. The maximum acceleration of a particle moving with simple harmonic motionis ____.
A. ω
B. ω.r
C. ω / 2 π
D. 2 π / ω
Answer:
B.ω.r
29. At the mean position, the potential energy of the system is _______.
A. Zero
B. Minimum
C. Maximum
D. None of the mentioned
Answer:
A.Zero
30. In a spring-mass-damper system, which of the following force is considered?
A. Spring force
B. Damping force
C. Accelerating force
D. All of the above
Answer:
D.All of the above
31. Frequency is equal to ______.
A. Time period
B. 1/time period
C. ω * time period
D. ω /time period
Answer:
B.1/time period
32. When the body vibrates under the influence of external force, then the bodyis said to be under ___________ .
A. Free vibrations
B. Natural vibrations
C. Forced vibrations
D. Damped vibrations
Answer:
C.Forced vibrations
33. A vertical spring-mass system has a mass of 0.5 kg and an initial deflectionof 0.2 cm. Find the spring stiffness.
A. 345 N/m
B. 245 N/m
C. 3452 N/m
D. 2452 N/m
Answer:
D.2452 N/m
34. A system has a mass of 0.5 kg and spring stiffness of 2452 N/m. Find thenatural frequency of the system.
A. 5.14 Hz
B. 9.14 Hz
C. 11.14 Hz
D. 28.14 Hz
Answer:
C.11.14 Hz
Free Vibration
35. The motion of a system executing harmonic motion with onenatural frequency is known as _______
A. principal mode of vibration
B. natural mode of vibration
C. both a. and b.
D. none of the above
Answer:
C.both a. and b.
36. 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:
A.Torsional vibrations do not occur in a three rotor system, if rotors rotate in same direction
37. In the diagram shown below, if rotor X and rotor Z rotate insame 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:
B.Two node vibration
38. What is the total number of nodes formed in a three rotor system ifthe rotors at one of the ends and the one in the middle rotate in the
A. 0
B. 1
C. 2
D. 3
Answer:
B.1
39. In a multi-rotor system of torsional vibration maximum number of nodes that can occur is:
A. Two
B. Equal to the number of rotor plus one
C. Equal to the number of rotors
D. Equal to the number of rotors minus one
Answer:
D.Equal to the number of rotors minus one
40. During torsional vibration of a shaft, the node is characterized by
A. Maximum angular velocity
B. Maximum angular displacement
C. Maximum angular acceleration
D. Zero angular displacement
Answer:
D.Zero angular displacement
41. The mass moment of inertia of the two motors in a two rotor systemare 100 kgm2 and 10 kgm2 the length of the shaft of uniform
A. 80 cm
B. 90 cm
C. 100 cm
D. 110 cm
Answer:
C.100 cm
42. What is the number of nodes in a shaft carrying three rotors?
A. zero
B. 2
C. 3
D. 4
Answer:
B.2
43. Consider the following statements: Two rotors mounted on a single shaft can be considered to be equivalent to a geared-shaft system having two rotors provided1. The kinetic energy of the equivalent system is equal to that of the original system. 2. The strain energy of the equivalent system is equal to that of the original system. 3. The shaft diameters of the two systems are equal. Which of these statements are correct?
A. 1, 2 and 3
B. 1 and 2
C. 2 and 3
D. 1 and 3
Answer:
A.1, 2 and 3
44. Two rotors A and B are connected to the two ends of a shaft ofuniform diameter. The mass moment of inertia of rotor A about the
A. 1/5 m
B. 4/5 m
C. 1/25 m
D. 16/25 m
Answer:
A.1/5 m
45. Which one of the following is correct for a shaft carrying two rotorsat its ends?
A. It has no node
B. It has one node
C. It has two nodes
D. It has three nodes
Answer:
B.It has one node
46. A system, which is free from both the ends
A. Definite system
B. Semidefinite system
C. Both a and b
D. None of the above
Answer:
B.Semidefinite system
47. A system, which is fixed from one end or both the ends is referredas
A. Definite system
B. Semidefinite system
C. Both a and b
D. None of the above
Answer:
A.Definite system
48. In a system with different shaft parameters, the longest shaft istaken for calculations.
A. TRUE
B. FALSE
Answer:
B.FALSE
49. In a system with different shaft parameters ————- is takenwhich depends on the length and diameters of each shaft.
A. Equivalent shaft length
B. length of first shaft
C. lrngth of intermediate shaft
D. None of these
Answer:
A.Equivalent shaft length
50. From the following data, calculate the location of node from the leftend of shaft (l1).l1=0.6m, l2=0.5m, l3=0.4m d1=0.095m, d2=0.06m, d3=0.05m Ma = 900 Kg, Mb = 700 Kg ka = 0.85m, kb = 0.55m
A. 0.855m
B. 0.795m
C. 0.695m
D. 0.595m
Answer:
A.0.855m
51. For a vibration system having different shaft parameters, calculatewhich of the following cannot be the diameter of the equivalent shaft if the diameters of shafts in m are: 0.05, 0.06, 0.07.
A. 0.05
B. 0.06
C. 0.07
D. 0.08
Answer:
D.0.08
52. A single cylinder oil engine works with a three rotor system, the shaft length is 2.5m and 70mm in diameter, the middle rotor is at a distance 1.5m from one end. Calculate the free torsional vibration frequency for a single node system in Hz if the mass moment of inertia of rotors in Kg-m2 are: 0.15, 0.3 and 0.09. C=84 kN/mm2
A. 171
B. 181
C. 191
D. 201
Answer:
A.171
53. At a nodal point in the shaft, the frequency of vibration is_________
A. Zero
B. Double than at the ends
C. Minimum
D. Maximum
Answer:
A.Zero
54. For a gearing system, the equivalent system is made consisting of two rotors. How many nodes will this new equivalent system will have?
A. 0
B. 1
C. 2
D. 3
Answer:
B.1
55. In a gearing system, pump speed is one third of the motor. Shaft from motor is 6 cm in diameter and 30cm long, the impellar shaft is 10cm diameter and 60cm long. Mass moment of inertia is 1500 Kgm2, C = 80Gn/m2. Neglecting the inertia of shaft and gears calculate the frequency of free torsional vibrations in Hz.
A. 4.7
B. 5.7
C. 4.5
D. 5.5
Answer:
A.4.7
56. When inertia of gearing is taken into consideration, then which ofthe following should be taken into account.
A. Addition of rotor
B. Addition of gear
C. Addition of shaft
D. Addition of pump
Answer:
A.Addition of rotor
57. Consider P and Q as the shaft having two rotors at the end of it,what is the point N known as in the given figure?
A. Node
B. Elastic point
C. Inelastic point
D. Breaking point
Answer:
A.Node
58. For occurrence of free torsional vibration which of the condition isnecessary?
A. Rotors moving in same direction
B. Rotors having same frequency
C. Rotors having different frequency
D. Rotors rotate in the same sense
Answer:
B.Rotors having same frequency
59. n the given figure if N is the node then NQ acts as which of thefollowing system?
A. Single rotor system
B. Two rotor system
C. Three rotor system
D. Four rotor system
Answer:
A.Single rotor system
60. Keeping the mass moment of inertia of both the shafts in a two rotor system same, if the length of one shaft is doubled what should be the effect on the length of other shaft?
A. Doubled
B. Halved
C. Constant
D. increased to 4 times
Answer:
A.Doubled
61. In the figure given below, the points N1 and N2 are knownas_______
A. Nodes
B. Elastic points
C. Inelastic points
D. Breaking points
Answer:
A.Nodes
62. In which of the following condition torsional vibration will not take place, considering 3 rotors A, B and C. A is rotating in clockwise direction.
A. B in clockwise C in anticlockwise
B. C in clockwise B in anticlockwise
C. B and C in clockwise
D. B and C in anticlockwise
Answer:
C.B and C in clockwise
63. For occurrence of free torsional vibration in a three rotor systemwhich of the condition is necessary?
A. Rotors moving in same direction
B. Rotors having same frequency
C. Rotors having different frequency
D. Rotors rotate in the same sense
Answer:
B.Rotors having same frequency
64. 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:
B.0.559 m
65. In a three rotor system, for the middle rotor, if the stiffness of boththe length either side of the rotor is increased to two times what will
A. Remains constant
B. Decreases by two times
C. Increases by two times
D. Increases by 4 times
Answer:
C.Increases by two times
66. Two heavy rotating masses are connected by shafts of length l1 , l2 and l3 and the corresponding diameters are d1 , d2 and d3 . This system is reduced to a torsionally equivalent system having uniform diameter d1 of the shaft. The equivalent length of the shaft is equal to
A.
B.
Answer:
D.
67. A single cylinder oil engine works with a three rotor system, the shaft length is 2.5m and 70mm in diameter, the middle rotor is at a distance 1.5m from one end. Calculate the free torsional vibration frequency for a two node system in Hz if the mass moment of inertia of rotors in Kg-m2 are: 0.15, 0.3 and 0.09. C=84 kN/mm2
A. 257
B. 281
C. 197
D. 277
Answer:
D.277
68. Increasing which of the following factor would result in increase of free torsional vibration?
A. Radius of gyration
B. Mass moment of inertia
C. Polar moment of inertia
D. Length
Answer:
C.Polar moment of inertia
69. The frequency of the free torsional vibration depends on…….
A. number of rotors
B. the number of nodes
C. Both a and b
D. Only b
Answer:
C.Both a and b
70. For a two rotor system, the mass moment of inertia of one shaft(A) is twice theother(B), then what is the relation between the length of the shafts.
A. 2L(A) = L(B)
B. L(A) = 2L(B)
C. L(A) = L(B)
D. 2L(A) = 3L(B)
Answer:
A.2L(A) = L(B)
Balancing
71. Which of the following is true for centrifugal force causing unbalance?
A. Direction changes with rotation
B. Magnitude changes with rotation
C. Direction and magnitude both change with rotation
D. Direction and magnitude both remain unchanged with rotation
Answer:
A.Direction changes with rotation
72. If the unbalanced system is not set right then.
A. Static forces develop
B. Dynamic forces develop
C. Tangential forces develop
D. Radial forces develop
Answer:
A.Static forces develop
73. What is the effect of a rotating mass of a shaft on a system?
A. Bend the shaft
B. Twist the shaft
C. Extend the shaft
D. Compress the shaft
Answer:
A.Bend the shaft
74. In a revolving rotor, the centrifugal force remains balanced as long as thecentre of the mass of the rotor lies ___________
A. Below the axis of shaft
B. On the axis of the shaft
C. Above the axis of shaft
D. Away from the axis of shaft
Answer:
B.On the axis of the shaft
75. Often an unbalance of forces is produced in rotary or reciprocating machinerydue to the ______
A. Centripetal forces
B. Centrifugal forces
C. Friction forces
D. Inertia forces
Answer:
D.Inertia forces
76. The mass used to balance the mass defect is known as ______
A. Balancing mass
B. Defect mass
C. Replacement mass
D. Fixing mass
Answer:
A.Balancing mass
77. In balancing of single-cylinder engine, the rotating unbalance is ____________
A. completely made zero and so also the reciprocating unbalance
B. completely made zero and the reciprocating unbalance is partially reduced
C. partially reduced and the reciprocating unbalance is completely made zero
D. partially reduced and so also the reciprocating unbalance
Answer:
B.completely made zero and the reciprocating unbalance is partially reduced
78. Let the disturbing mass be 100 kg and the radius of rotation be 10 cm and therotation speed be 50 rad/s, then calculate the centrifugal force in kN.
A. 50
B. 25
C. 50000
D. 25000
Answer:
B.25
79. Which of the following statement is correct?
A. In any engine, 100% of the reciprocating masses can be balanced dynamically
B. In the case of balancing of multicylinder engine, the value of secondary force is higher than the value of the primary force
C. In the case of balancing of multimass rotating systems, dynamic balancing can be directly started without static balancing done to the system
D. none of the mentioned
Answer:
C.In the case of balancing of multimass rotating systems, dynamic balancing can be directly started without static balancing done to the system
80. If all the masses are in one plane, then what is the maximum no. of masseswhich can be placed in the same plane?
A. 3
B. 4
C. 6
D. No limitation
Answer:
D.No limitation
81. Which of the following statements is correct about the balancing of amechanical system?
A. If it is under static balance, then there will be dynamic balance also
B. If it is under dynamic balance, then there will be static balance also
C. Both static as well as dynamic balance have to be achieved separately
D. None of the mentioned
Answer:
C.Both static as well as dynamic balance have to be achieved separately
82. In a locomotive, the ratio of the connecting rod length to the crank radius iskept very large in order to
A. minimize the effect of primary forces
B. minimize the effect of secondary forces
C. have perfect balancing
D. start the locomotive conveniently
Answer:
B.minimize the effect of secondary forces
83. Secondary forces in reciprocating mass on engine frame are
A. of same frequency as of primary forces
B. twice the frequency as of primary forces
C. four times the frequency as of primary forces
D. none of the mentioned
Answer:
B.twice the frequency as of primary forces
84. For a V-twin engine, which of the following means can be used to balance theprimary forces?
A. Revolving balance mass
B. Rotating balance mass
C. Reciprocating balance mass
D. By the means of secondary forces
Answer:
A.Revolving balance mass
85. The primary unbalanced force is maximum when the angle of inclination of thecrank with the line of stroke is
A. 0°
B. 90°
C. 180°
D. 360°
Answer:
C.180°
86. From the following data of a 60 degree V-twin engine, determine the minimum value for primary forces in newtons:Reciprocating mass per cylinder = 1.5 Kg Stroke length = 10 cm Length of connecting rod = 25 cm Engine speed = 2500 rpm
A. 7711
B. 4546
C. 2570
D. 8764
Answer:
C.2570
87. From the following data of a 60 degree V-twin engine, determine the maximum value for primary forces in newtons:Reciprocating mass per cylinder = 1.5 Kg Stroke length = 10 cm Length of connecting rod = 25 cm Engine speed = 2500 rpm
A. 7711
B. 4546
C. 2570
D. 8764
Answer:
A.7711
88. In the given figure, m1=10 Kg, m2=30Kg and m=50 Kg, if r=0.3m, l=1m, findl2 = 0.5m, find r1 in m.
A. 1.5
B. 0.75
C. 3
D. 6
Answer:
B.0.75
89. From the given data, find the balancing mass’s inclination in degrees if r=0.2m required in the same plane.Masses = 200kg, 300kg, 240 kg, 260Kg,
A. 201.48
B. 200.32
C. 210.34
D. 202.88
Answer:
A.201.48
90. Which of the following statements are associated with complete dynamic balancing of rotating systems? 1. Resultant coupledue to all inertia forces is zero. 2. Support reactions due to forces are zero but not due to couples . 3. The system is automatically statically balanced. 4. Centre of masses of the system lies on the axis of rotation.
A. 1, 2, 3 and 4
B. 1, 2, and 3 only
C. 2, 3 and 4 only
D. 1, 3 and 4 only
Answer:
D.1, 3 and 4 only
91. A V-twin engine has the cylinder axes at 90 degrees and the connecting rods operate a common crank. The reciprocating mass per cylinder is 11.5 kg and the crank radius is 7.5 cm. The length of the connecting rod is 0.3 m. If the engine is rotating at the speed is 500 r.p.m. What is the value of maximum resultant secondary force in Newtons?
A. 736
B. 836
C. 936
D. 636
Answer:
B.836
92. Let the centrifugal force in kN be 25 and the radius of rotation be 20 cm andthe rotation speed be 50 rad/s, then calculate the mass defect in Kg.
A. 50
B. 25
C. 50000
D. 25000
Answer:
A.50
93. In a multicylinder inline engine, each imaginary secondary crank with a massattached to the crankpin is inclined to the line of stroke at which angle?
A. Twice the angle of crank
B. Half the angle of crank
C. Thrice the angle of crank
D. Four times the angle of crank
Answer:
A.Twice the angle of crank
94. In order to achieve stability, the sum of secondary forces and secondarycouples must be ——- and their respective polygons must be ………
A. Zero, Closed
B. one, Open
C. Zero, open
D. one, closed
Answer:
A.Zero, Closed
95. For the secondary balancing of the engine, which of the condition is necessary?
A. Secondary force polygon must be close
B. Secondary force polygon must be open
C. Primary force polygon must be close
D. Primary force polygon must be open
Answer:
A.Secondary force polygon must be close
96. The numerical values of the secondary forces and secondary couples couplesmay be obtained by considering the ___________
A. Revolving mass
B. Reciprocating mass
C. Translating mass
D. Rotating mass
Answer:
A.Revolving mass
97. Which of the following is the correct expression for secondary force?
A. m𝜔^2r.cos2θ/n
B. m 𝜔^2r.sin2θ/n
C. m𝜔^2r.tan2θ/n
D. m𝜔^2r.cosθ/n
Answer:
A.m𝜔^2r.cos2θ/n
98. A V-twin engine has the cylinder axes at 90 degrees and the connecting rods operate a common crank. The reciprocating mass per cylinder is 23 kg and the crank radius is 7.5 cm. The length of the connecting rod is 0.3 m. If the engine is rotating at the speed is 500 r.p.m. What is the value of maximum resultant secondary force in Newtons?
A. 7172
B. 1672
C. 1122
D. 1272
Answer:
B.1672
99. A V-twin engine has the cylinder axes at 90 degrees and the connecting rods operate a common crank. The reciprocating mass per cylinder is 34.5 kg and the crank radius is 7.5 cm. The length of the connecting rod is 0.3 m. If the engine is rotating at the speed is 500 r.p.m. What is the value of maximum resultant secondary force in kN?
A. 2.238
B. 2.508
C. 2.754
D. 2.908
Answer:
B.2.508
100. From the given data, find the balancing mass in Kg if r=0.2m required in the same plane.Masses = 200kg, 300kg, 240 kg, 260Kg, corresponding radii = 0.2m, 0.15m, 0.25m and 0.3m.Angles between consecutive masses = 45, 75 and 135 degrees.
A. 116
B. 58
C. 232
D. 140
Answer:
A.116
101. Let the disturbing mass be 200 kg and the radius of rotation be 20 cm and therotation speed be 50 rad/s, then calculate the centripetal force in kN.
A. -50
B. -25
C. -100
D. -2500
Answer:
C.-100
102. From the given data, calculate the unbalanced centrifugal force in N s2Distance from shaft = 0.2 m Mass = 100 kg Rotating speed = 1000 rpm.
A. 20
B. 2×10^7
C. 200
D. 20000
Answer:
C.200
103. Let the disturbing mass be 50 Kg, with radius of rotation = 0.1m, if one of the balancing mass is 30 Kg at a radius of rotation 0.1m then find the other balancing mass situated at a distance of 0.2m.
A. 80
B. 40
C. 20
D. 10
Answer:
D.10
104. In the given figure, m1=20 Kg, m2=30Kg and m=50 Kg, if r1=0.2m andr=0.3m, l=1m, find l2.
A. 0.26m
B. 0.52m
C. 1.04m
D. 13m
Answer:
A.0.26m
Measurement and Control of Vibration
105. What is the function of frequency analyzer?
A. It analysis noise signal in frequency domain into various frequency bands by magnetically separating the signal
B. It analysis noise signal in frequency domain into various frequency bands by electronically separating the signal
C. It analysis noise signal in frequency domain into various frequency bands by electromagnetically separating the signal
D. None of the above
Answer:
B.It analysis noise signal in frequency domain into various frequency bands by electronically separating the signal
106. What is the function of the controller in active vibration isolation systems?
A. Detect vibrations to be controlled
B. Reposition the masses
C. Interpret detected vibrations and execute commands
D. All of the above
Answer:
C.Interpret detected vibrations and execute commands
107. Temperature monitoring technique uses which of the following devices to measure temperature of the machining surfaces?
A. Pyrometers
B. Thermocouples
C. Thermometers
D. All of the above
Answer:
D.All of the above
108. Which of the following statements is true about stroboscope?
A. Stroboscope is non-contact type frequency instrument
B. Stroboscope can measure frequency upto 5 Hz
C. Stroboscope uses electromagnetic radiations to measure frequency
D. All of the above
Answer:
A.Stroboscope is non-contact type frequency instrument
109. Which type of frequency measuring instrument has multiple reeds of different naturalfrequency to measure vibrations?
A. Fullarton tachometer
B. Frahm Tachometer
C. Both a. and b.
D. None of the above
Answer:
B.Frahm Tachometer
110. Which of the following instruments measure amplitude of a vibrating body?
A. Vibrometers
B. Seismometer
C. Both a. and b.
D. None of the above
Answer:
C.Both a. and b.
111. 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:
A.Accelerometers
112. 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:
B.Basic condition monitoring system
113. 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:
C.both a. and b.
114. In FFT Spectrum Analyzer, the D/A converter is used to ________.
A. reject unwanted signals
B. sets the level of the signals to be fed to the A/D converter
C. convert analog signals into digital signals
D. converts digital signals into analog signals
Answer:
D.converts digital signals into analog signals
115. In FFT Spectrum Analyzer, the A/D converter is used to ________.
A. reject unwanted signals
B. sets the level of the signals to be fed to the A/D converter
C. convert analog signals into digital signals
D. converts digital signals into analog signals
Answer:
C.convert analog signals into digital signals
116. In FFT Spectrum Analyzer, the attenuator is used to ________.
A. reject unwanted signals
B. sets the level of the signals to be fed to the A/D converter
C. convert analog signals into digital signals
D. converts digital signals into analog signals
Answer:
B.sets the level of the signals to be fed to the A/D converter
117. In FFT Spectrum Analyzer, the filter is used to ________.
A. reject unwanted signals
B. sets the level of the signals to be fed to the A/D converter
C. convert analog signals into digital signals
D. converts digital signals into analog signals
Answer:
A.reject unwanted signals
118. FFT analyzer can be used to find the ___________.
A. natural frequencies
B. mode shapes
C. both natural frequencies and mode shapes
D. none of the above
Answer:
C.both natural frequencies and mode shapes
119. Fourier transform is a mathematical procedure to obtain the __________ of a given inputsignal.
A. spectrum
B. integration
C. difference
D. none of the above
Answer:
A.spectrum
120. In FFT Spectrum Analyzer, FFT stands for _______.
A. Frequency Fourier Transform
B. Fast Fourier Transmission
C. Frequency Fourier Transmission
D. Fast Fourier Transform
Answer:
D.Fast Fourier Transform
121. From the following, which one is used in an accelerometer?
A. Dielectric crystals
B. Piezoelectric crystals
C. Optic crystals
D. Diamond
Answer:
B.Piezoelectric crystals
122. The accelerometers are commonly used in vibration measurement due to their ___________.
A. small size and low sensitivity
B. the large size and high sensitivity
C. the large size and low sensitivity
D. small size and high sensitivity
Answer:
D.small size and high sensitivity
123. Which instrument is used to record building vibrations or vibrations of huge structures like railway bridges?
A. Stroboscope
B. Accelerometer
C. Vibrometer
D. None of the above
Answer:
C.Vibrometer
124. Vibration measuring instruments are classified on the basis of ____________.
A. contact between the vibrating system and measuring instrument
B. the requirement of power source
C. method of measurements
D. all of the above
Answer:
D.all of the above
125. From the following, which one is also known as low-frequency Transducer?
A. Stroboscope
B. Accelerometer
C. Vibrometer
D. None of the above
Answer:
C.Vibrometer
126. From the following, which one is a type of vibration measuring instrument?
A. Mechanical
B. Electrical
C. Magnetic
D. All of the above
Answer:
D.All of the above
127. An accelerometer is an instrument used to measure the _________ of a vibrating body.
A. displacement
B. velocity
C. acceleration
D. all of the above
Answer:
C.acceleration
128. Stroboscope is used for the measurement of _________________?
A. Rpm of a flywheel
B. Frequency of light
C. Depression of freezing point
D. Liquid level under pressure
Answer:
A.Rpm of a flywheel
129. A seismometer is a device used to measure the ___________ of a vibrating body.
A. displacement
B. velocity
C. acceleration
D. all of the above
Answer:
A.displacement
130. The instruments which are used to measure the ___________ of a vibrating body arecalled vibration measuring instrument.
A. displacement
B. velocity
C. acceleration
D. all of the above
Answer:
D.all of the above
131. The accelerometer is used as a transducer to measure earthquake in Richter scale. Itsdesign is based on the principle that ______.
A. its natural frequency is very low in comparison to the frequency of vibration
B. its natural frequency is very high in comparison to the frequency of vibration
C. its natural frequency is equal to the frequency of vibration
D. measurement of vibratory motion is without any reference point
Answer:
C.its natural frequency is equal to the frequency of vibration
132. Which of the following instruments measure the amplitude of a vibrating body?
A. Vibrometers
B. Seismometer
C. Both (a) and (b)
D. None of these
Answer:
C.Both (a) and (b)
133. Which of the following systems produce a vibration in the foundation?
A. Coupled machine
B. Uncoupled machine
C. Balanced machine
D. Unbalanced machine
Answer:
D.Unbalanced machine
134. What does the accelerometer measure?
A. Mass
B. Acceleration
C. Velocity
D. Distance
Answer:
B.Acceleration
135. Which of the following device can be used for measurement of frequency?
A. Voltmeter
B. Ammeter
C. Stroboscope
D. None of the mentioned
Answer:
C.Stroboscope
136. Which of the following is correct regarding isolation factor?
A. Dimensionless quantity
B. Has Newton as its unit
C. Has joule as its Unit
D. Has Hz as its unit
Answer:
A.Dimensionless quantity
137. If the damper is not provided and the system is in resonance, which of the following is the correctisolation factor?
A. 0
B. 0.5
C. 0.25
D. Infinity
Answer:
D.Infinity
Introduction to Noise
138. Which part of human ear converts sound vibrations into electrical signals
A. Hammer
B. Stirrup
C. Tympanic membrane
D. Cochlea
Answer:
D.Cochlea
139. Sound is measured by units that are called
A. Hertz (Hz)
B. Decibels (dB)
C. Meters (m)
D. Pascal (Pa)
Answer:
B.Decibels (dB)
140. ‘Eardrum’ bursts at
A. 40 dB
B. 80 dB
C. 160 dB
D. 320 dB
Answer:
C.160 dB
141. The loudness of sound varies directly with the vibrating body’s
A. Intensity
B. Amplitude
C. Pitch
D. Quality
Answer:
B.Amplitude
142. The scale to measure the intensity level of sound is called
A. Vector scale
B. Measuring ruler
C. Bel scale
D. decibel scale
Answer:
D.decibel scale
143. Pitch of the sound depends upon
A. Frequency
B. Distance of sound
C. Amplitude
D. Temperature
Answer:
A.Frequency
144. Noise is
A. An unwanted noise
B. An irritant
C. A source of stress
D. all of the above
Answer:
D.all of the above
145. Following scale is used for loudness of sound or noise
A. Linear scale
B. Logarithmic scale
C. Exponential scale
D. None of the above
Answer:
B.Logarithmic scale
146. Sound Intensity is given by.
A. I=w/s
B. I=s/w
C. w=I/s
D. s=w/I
Answer:
A.I=w/s
147. Unit for Reference sound intensity is_________.
A. W/m2
B. W/mm3
C. W/cm3
D. None of the above
Answer:
A.W/m2
148. Sound power of a machine whose specified sound power level is 125 dB
A. 3.16 w
B. 4.2w
C. 5w
D. 31.6w
Answer:
A.3.16 w
149. The process of maintaining appropriate noise level without consideringeconomic factors is called as _____
A. noise control
B. noise reduction
C. both a. and b.
D. none of the above
Answer:
B.noise reduction
150. Basic elements of noise control are
A. Source ,Path ,Receiver of noise
B. Amplitude and Frequency
C. Time period
D. A and B both
Answer:
A.Source ,Path ,Receiver of noise
151. All sound is noise.
A. TRUE
B. False
C. none
D. none
Answer:
B.False
152. Main sources of noise pollution are
A. Transportation equipment only
B. Heavy machinery only
C. Musical instruments
D. Transportation equipment and heavy machinery
Answer:
D.Transportation equipment and heavy machinery
153. The sound can travel in air when:
A. Particles of medium travel from one place to another
B. There is no moisture in the atmosphere
C. Disturbance travel from one place to another
D. Both particles as well as disturbance travel from one place to another
Answer:
C.Disturbance travel from one place to another
154. White noise is random noise that has a audible frequency rangefrom
A. 320 to 100 KHz
B. 20 to 20KHtz
C. 120 to 20KHtz
D. 220 to 20KHtz
Answer:
B.20 to 20KHtz
155. Which among the following has a constant power spectral density over a widefrequency range?
A. White noise
B. Black noise
C. Pink noise
D. Blue noise
Answer:
A.White noise
156. Which is correct option for ear protection equipment?
A. Headphone
B. Use of cotton in ears
C. Ear defeders ,Ear plugs
D. All the above
Answer:
C.Ear defeders ,Ear plugs
157. The technique or method to absorb undesirable sounds by soft and porous
A. Acoustic protection
B. Unacoustic protection
C. Audible protection
D. Decibel protection
Answer:
A.Acoustic protection
158. When sound interacts with materials and boundaries, it displays all the
A. Heat
B. Waves
C. Light
D. Electricity
Answer:
B.Waves
159. Soft materials absorb a large amount of
A. Heat energy
B. Light energy
C. Electromagnetic waves
D. Sound energy
Answer:
D.Sound energy
160. Reflection coefficient (Γ) is the rario of intensity of sound ______________.
A. Reflected / Incident.
B. Incident / Reflected.
C. Absorbed / Reflected.
D. None of the above.
Answer:
A.Reflected / Incident.
161. Absorption coefficient (α) is the rario of intensity of sound ______________.
A. Absorbed / Incident.
B. Incident / Reflected.
C. Absorbed / Incident.
D. None of the above.
Answer:
C.Absorbed / Incident.
162. Which best describe the sound wave?
A. It may be longitudinal
B. It is always transverse
C. It is always longitudinal
D. All of the above
Answer:
C.It is always longitudinal
163. Which of the following can not travel through a vacuum?
A. Electromagnetic wave
B. Radio wave
C. Sound wave
D. Light wave
Answer:
C.Sound wave
164. Through which medium does sound travel fastest?
A. Air
B. Steel
C. Water
D. Mercury
Answer:
B.Steel
165. Sound wave has two main characteristics which are
A. Pitch and loudness
B. Tone and loudness
C. Highness and loudness
D. Rarefaction and compression
Answer:
A.Pitch and loudness
166. When waves bend away from straight lines of travel, it is called
A. Reflection
B. Diffraction
C. Rarefaction
D. Refraction
Answer:
D.Refraction
167. _________ is the sound power measured over the area upon which is received.
A. Sound pressure
B. Sound energy
C. Sound intensity
D. Sound pressure level
Answer:
C.Sound intensity
168. It is an audio transducer that converts acoustic pressure in air into its equivalentelectrical impulses
A. Loudspeaker
B. Amplifier
C. Baffle
D. Microphone
Answer:
D.Microphone
169. _________ is a pressure type microphone with permanent coil as a transducingelement.
A. Dynamic
B. Condenser
C. Magnetic
D. Carbon
Answer:
A.Dynamic
170. A capacitor stores energy in the form of an electrostatic field is a ______.
A. Dynamic Microphone
B. Condenser Microphone
C. Magnetic Microphone
D. Carbon Microphone
Answer:
B.Condenser Microphone
171. Which type of vibrations are also known as transient vibrations?
A. Undamped vibrations
B. Damped vibrations
C. Torsional vibrations
D. Transverse vibrations
Answer:
B.Damped vibrations
172. During transverse vibrations, shaft is subjected to which type of stresses?
A. Tensile stresses
B. Torsional shear stress
C. Bending stresses
D. All of the above
Answer:
C.Bending stresses
173. 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:
A.Vibrations caused due to known exciting force
174. Which of the following vibrations are classified according to magnitude ofactuating force?
A. Torsional vibrations
B. Deterministic vibrations
C. Transverse vibrations
D. All of the above
Answer:
B.Deterministic vibrations
175. In which type of vibrations, amplitude of vibration goes on decreasing everycycle?
A. Damped vibrations
B. Undamped vibrations
C. Both a. and b.
D. None of the above
Answer:
A.Damped vibrations