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MULTIPLE CHOICE QUESTIONS (MCQ) WITH ANSWERS ON VIBRATIONS

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MCQ MULTIPLE CHOICE

QUESTIONS (MCQ) WITH

ANSWERS ON VIBRATIONS

 

MCQ increases depth of understanding. It

gives a high degree of clarity. Vibration is

a periodic motion. It is like reversal

loading. It is highly dangerous. Vibrations

are free & forced vibrations with /without

damping. Vibrations causes unpleasant

sound. It weakens the foundation of a

structure.

  1. The most salient features of any vibration are

    1. Amplitude & acceleration

    2. Frequency & acceleration

    3. Amplitude & frequency

    4. None

ANS: (c)

  1. One Hertz is equal to

  1. 3 cycles per second

  2. 6 cycles per second

  3. 9 cycles per second

  4. None

ANS: (d)

  1. One Hertz means

  1. 3 cycles per second

  2. 1 cycle per second

  3. 2 cycles per second

  4. None

ANS: (b)

  1. During vibration, speed of motion is

  1. Constant

  2. Variable

  3. Can’t say

  4. None

ANS: (b)

  1. During each cycle of vibration, the magnitude of acceleration range as the object moves from its stationary position

  1. Firstly                       0 to 10 m/s2

  2. Secondly                  0 to 20 m/s2

  3. Thirdly                     0 to maximum

  4. None

ANS: (c)

  1. A structure under vibration is under

  1. Constant load

  2. Variable load

  3. Reversing load

  4. None

ANS: (c)

  1. A reversing load

  1. Increases the strength

  2. Decreases the strength

  3. Do not affect the strength

  4. None

ANS: (b)

  1. Acceleration of a vibration is zero at the

  1. Extreme left

  2. Extreme right

  3. Mean position

  4. None

ANS: (c)

  1. Vibration is a phenomenon

  1. Mechanical

  2. Electrical

  3. Civil

  4. None

ANS: (a)

  1. Vibrations are

  1. Desirable

  2. Undesirable

  3. Both (a) & (b)

  4. None

ANS: (c)

  1. The desirable vibrations is in a

  1. Mobile phone

  2. Moving electric motor

  3. Moving engine

  4. None

ANS: (a)

  1. The undesirable vibration is in a

  1. Mobile phone

  2. Electric motor

  3. Both (a) & (b)

  4. None

ANS: (b)

  1. The vibrations is

  1. Periodic

  2. Random

  3. Both (a) & (b)

  4. None

ANS: (c)

  1. Types of vibrations are

  1. Free & forced

  2. Damped

  3. Both (a) & (b)

  4. None

ANS: (c)

  1. Identify a free vibration

  1. Pulling a child back on a swing

  2. Hitting a tuning fork

  3. Both (a) & (b)

  4. None

ANS: (c)

  1. Identify a forced vibration

  1. Pulling a child back on a swing

  2. Vibration of a building due to earthquake

  3. Both (a) & (b)

  4. None

ANS: (b)

  1. Identify a damped vibration

  1. Vibration of a vehicle on an uneven road

  2. Vehicular suspension system

  3. Both (a) & (b)

  4. None

ANS: (b)

  1. Free vibration of a mechanical system comes from

  1. Individual disturbance

  2. Continuous disturbance

  3. Both (a) & (b)

  4. None

ANS: (a)

  1. Forced vibration of a mechanical comes from

  1. Single disturbance

  2. Continuous disturbance

  3. Both single and continuous disturbance

  4. None

ANS: (b)

  1. A damped vibration of a mechanical comes from a

  1. Shock absorber

  2. Friction

  3. Both shock absorber & friction

  4. None

ANS: (c)

  1. Low frequency vibration is

  1. > 100 HZ

  2. <100 HZ

  3. > 2000HZ

  4. None

ANS: (b)

  1. High frequency vibration is of

  1. <100 HZ

  2. > 2000 HZ
  3. ≤ 2000 HZ
  4. None

ANS: (c)

  1. In mechanical vibrations, it is desirable to achieve

  1. Resonance

  2. Anti-resonance

  3. Can’t say

  4. None

ANS: (b)

  1. Identify the equation of natural frequency

  1. f =(1/π) (k/m)5

  2. f =(1/3π)(k/m)5

  3. f=(1/4π)(k/m))5

  4. None

ANS: (d)

  1. Identify the equation of natural frequency

    1. f =(1/4π) (k/m)5

    2. f =(1/6π)(k/m)5

    3. f=(1/2π)(k/m))5

    4. None

ANS: (c)

  1. Identify the equation of natural frequency

  1. F =(1/π) (k/m)5

  2. F =(1/3π)(k/m)5

  3. F=(1/4π)(k/m))5

  4. None

ANS: (d)

  1. Damping force is proportional to the

  1. Displacement

  2. Velocity

  3. Acceleration

  4. None

ANS: (b)

  1. In the absence of a damping, the vibration will stop

  1. After 10 minutes

  2. Immediately

  3. Never

  4. None

ANS: ©

  1. Vibration produces sound. Sound includes the vibrations of the

  1. Object and air molecules

  2. Eardrum

  3. Both (a) & (b)

  4. None

ANS: (c)

  1. The slowest vibration frequency the human ear hears is

  1. 10 HZ

  2. 20 HZ

  3. 100 Hz

  4. None

ANS: (b)

  1. The fastest vibration frequency the human ear hears is

  1. 1lac HZ

  2. 3 lac HZ

  3. 2 lac Hz

  4. None

ANS: (c)

  1. Vibrations exists in

  1. Inelastic bodies

  2. Elastic bodies

  3. Both elastic & inelastic bodies

  4. None

ANS: (b)

  1. Vibration is a friend in a

  1. Compressor

  2. Pneumatic drill

  3. Both compressor & pneumatic drill

  4. None

ANS: (b)

  1. Vibration is a foe in a

  1. Compressor

  2. Pneumatic drill

  3. Both compressor & pneumatic drill

  4. None

ANS: (a)

  1. Periodic motion is that motion which repeats itself after

  1. Different intervals of time

  2. Equal intervals of time

  3. Both equal and different intervals of time

  4. None

ANS: (b)

  1.  Time taken for one complete vibration is time period in

  1. Hours

  2. Minutes

  3. Seconds

  4. None

ANS: (c)

  1. Simple harmonic motion is motion of a particle with time in a circle with uniform

  1.  Tangential velocity

  2.  Axial velocity

  3. Radial velocity

  4. None

ANS: (a)

  1. The natural frequency of a system is the

  1. Forced vibrations

  2. Damped vibrations

  3. Free vibrations

  4. None

ANS: (c)

  1. Natural frequency of a certain system is

  1. Variable

  2. Constant

  3. Variable and constant

  4. None

ANS: (b)

  1. Resonance produces when vibration of a system under an external force is equal to the

  1. Four times the natural frequency

  2. Two times the natural frequency

  3. Three times the natural frequency

  4. None

ANS: (d)

  1. The amplitude of vibration at resonance is

  1. Very small

  2. Very large

  3. Average

  4. None

ANS: (b)

  1. At resonance condition with minimum input, output is

  1. Medium

  2. Minimum

  3. Maximum

  4. None

ANS: (c)

  1. Damping keeps vibrations

  1. Constant

  2. Decreases

  3. Increases

  4. None

ANS: (b)

  1. Types of free vibrations are

  1. Longitudinal & Transverse

  2. Transverse & torsional

  3. Longitudinal, transverse & torsional

  4. None

ANS: (c)

  1. The free vibrations means no time varying

  1. External force acts

  2. Internal force acts

  3. Both (a) & (b)

  4. None

ANS: (a)

  1. Time ‘ T ‘ required to complete one vibration is

  1. T=2π ω0

  2. T =2π + ω0

  3. T =2π /ω0

  4. None

ANS: (c)

  1. The natural frequency ‘ ω0 ‘ of free vibration is

  1. Firstly                        ωo =(k/m)

  2. Secondly                    ωo =(k/m) 45

  3. Thirdly                       ωo =(k/m)5

  4. None

ANS: (c)

  1. The differential equation for free undamped vibration for mass ‘m’ , spring stiffness ’k’ & displacement ‘x’ from the equilibrium position is

  1. Firstly                                      m d2x/d2t +k x =C

  2. Secondly                                  m d2x/d2t +k x =0

  3. Thirdly                                      m d2x/d2t +k2 x =0

  4. None

ANS: (b)

  1. The solution of free undamped vibration equation ‘m d2x/d2t +k x =0 is

  1. Firstly                                  x=2A Cos (k/m)5 + B Sin (k/m)0.5

  2. Secondly                              x=A Cos (k/m)5 + 2B Sin (k/m)0.5

  3. Thirdly                                  x=A Cos (k/m)5 + B Sin (k/m)0.5

  4. None

ANS: (c)

  1. Critical damping coefficient is

  1. Firstly                        Cc = 2(k m)5

  2. Secondly                   Cc = 2km

  3. Thirdly                      Cc=2 k/m

  4. None

ANS: (a)

  1. The differential equation for free vibrations with viscous damping coefficient ‘c’ is

    1. Firstly                               m d2x/d2t +c + k x =C

    2. Secondly                          m d2x/d2t +c dx/dt +k x =0

    3. Thirdly                              m d2x/d2t +cx +k2 x =0

    4. None

ANS: (b)

  1. Damping is less than critical damping. Then solution of the differential equation m d2x/d2t +c dx/dt +k x =0 with damped natural frequency’ ωd ‘ is

  1. Firstly                          x = e-c t/m (A Sin ωd t +B Cos ωdt)

  2. Secondly                     x = e-c t/2m (A Sin ωd t +B Cos ωdt)

  3. Thirdly                        x = e-c t/4m (A Sin ωd t +B Cos ωdt)

  4. None

ANS: (b)

  1. The relation of damped natural and undamped natural frequency is

  1. Firstly                              ωd = ω0 (1-ζ ) 5

  2. Secondly                            ωd = ω0 (1-ζ 3 )5

  3. Thirdly                                ωd = ω0 (1-ζ 2 )5

  4. None

ANS: (c)

  1. Solution of the differential equation m d2x/d2t +c dx/dt +k x =0 with damped natural frequency’ ωd ‘ and critical damping is

  1. Firstly                                       x = e-c t/m (A Sin ωd t +B Cos ωdt)

  2. Secondly                                   x = e-c t/2m (A +Bt)

  3. Thirdly                                      x = e-c t/4m (A – Bt)

  4. None

ANS: (b)

  1. Differential equation of forced vibration with Sinusoidal force = F0 Sin ωt ‘ without damping is

  1. Firstly                                  m d2x/d2t +k x =C F0 Sin ωt

  2. Secondly                             m d2x/d2t +k x =C

  3. Thirdly                                 m d2x/d2t +k2 x = F0 Sin ωt

  4. None

ANS: (c)

  1. Differential equation of forced vibration with Sinusoidal force = F0 Sin ωt ‘ with damping is

  1. Firstly                                  m d2x/d2t +c dx/dt + k x = F0 Sin ωt

  2. Secondly                             m d2x/d2t + c dx/dt + k x =C

  3. Thirdly                                 m d2x/d2t +c dx/dt + k2 x = F0 Sin ωt

  4. None

ANS: (a)