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

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

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

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

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

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

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

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

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

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

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

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