Mechanical Vibration MCQ

31. If there is a gradual reduction in amplitude of vibration with time, the body is said to be in

  1. Free vibration
  2. Forced vibration
  3. Damped vibration
  4. Undamped vibration
Answer
Answer. c

32. In forced vibration, the magnitude of the damping force at resonance equals to

  1. Inertia force
  2. Impressed force
  3. Spring force
  4. Zero
Answer
Answer. b

33. The critical speed of a shaft is affected by its

  1. Eccentricity
  2. Span
  3. Diameter

Which of the above are correct?

  1. i and ii
  2. i and iii
  3. ii and iii
  4. i, ii and iii
Answer
Answer. d

34. In underdamped vibration system, the amplitude of the vibration with reference to time

  1. remains constant
  2. increase exponentially
  3. decrease exponentially
  4. increase linearly
Answer
Answer. c

35. In a spring-mass of the system is made half and the spring stiffness is doubled. The natural frequency of longitudinal vibration is

  1. Doubled
  2. Halved
  3. Quaderupled
  4. Constant
Answer
Answer. a

36. Rotating shaft’s tend to vibrate violently in _________ at critical speeds.

  1. Longitudinal direction
  2. Transverse direction
  3. Torsional direction
  4. None of the above
Answer
Answer. b

37. In forced vibrations, magnitude of damping force at resonance equals

  1. impressed force
  2. inertia force
  3. spring force
  4. infinity
Answer
Answer. a

38. The ratio of the amplitude of the steady state response to the static deflection under the action of a force is known as

  1. Damping factor
  2. Magnification factor
  3. Frequency ratio
  4. Damping coefficient
Answer
Answer. b

39. Whirling speed of a shaft coincide with the natural frequency of the

  1. Longitudinal vibration
  2. Transverse vibration
  3. Torsional vibration
  4. Coupled between torsional vibration
Answer
Answer. b

40. In a damped vibration system, the damping force is proportional to

  1. displacement
  2. velocity
  3. acceleration
  4. vibrations
Answer
Answer. b