Question

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

(a) perpendicular to its axis

(b) parallel to its axis

(c) in a circle about its axis

(d) none of the mentioned

The question was posed to me during an interview.

My question is from Vibratory Motion topic in chapter Longitudinal and Transverse Vibrations of Machine Dynamics

Answer 1

Right option is (b) parallel to its axis

To explain: When the particles of the shaft or disc moves parallel to the axis of the shaft, then the vibrations are known as longitudinal vibrations.

When the particles of the shaft or disc move approximately perpendicular to the axis of the shaft, then the vibrations are known as transverse vibrations.