Mechanical Vibration MCQ

51. A boy is swinging on a swing. If another boy sits along with him without disturbing his motion, then the time period of swing will

1. increase
2. decrease
3. be doubled
4. remain the same

52. Longitudinal vibrations are said to occur when the particles of a body moves

1. perpendicular to its axis
2. parallel to its axis
3. in a circle about its axis
4. none of these

53. A vibrating beam has following degrees of freedom

1. 1
2. 0
3. 3
4. 2

54. Which one of the following laws is not applicable for a simple pendulum?

1. the time period does not depend on its magnitude
2. the time period is proportional to its length
3. the time period is proportional to square root of its length
4. the time period is inversely proportional to square root of its acceleration due to gravity

55. If damping factor in a vibrating system is unity, then the system will be

1. highly damped
2. not damped
3. critically damped
4. under damped

56. The critical speed depends on

1. mass
2. stiffness
3. mass and stiffness
4. mass, stiffness, and eccentricity

57. A torsional vibratory system having two rotors connected by a shaft has

1. One node
2. Two nodes
3. Three nodes
4. No node

58. A three rotor system has following number of natural frequencies

1. 2
2. 1
3. 4
4. 3

59. The critical speed of a rotating shaft with a mass at the centre is _________ the natural frequency of transverse vibration of the system.

1. less than
2. equal
3. more than
4. dependent upon

60. In under-damped vibrating system, the amplitude of vibration with reference to time

1. increases linearly
2. increases exponentially
3. decreases linearly
4. decreases exponentially