DOM III Unit II

1. When there is a reduction in amplitude over every cycle of vibration, then the body is said to have

• a) free vibration

• b) forced vibration

• c) damped vibration

• d) none of the mentioned

2. 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

3. When a body is subjected to transverse vibrations, the stress induced in a body will be

• a) shear stress

• b) tensile stress

• c) compressive stress

• d) none of the mentioned

5. The factor which affects the critical speed of a shaft is

• a) diameter of the disc

• b) span of the Beam

• c) eccentricity of fixed support

• d) all of the mentioned

When a body is subjected to transverse vibrations, the stress induced in a body will be

• a) shear stress

• b) bending stress

• c) tensile stress

• d) compressive stress

The critical speed of a shaft with a disc supported in between is equal to the natural frequency of the system in

• a) transverse vibrations

• b) torsional vibrations

• c) longitudinal vibrations

• d) none of the mentioned

In steady state forced vibrations, the amplitude of vibrations at resonance is _____________ damping coefficient.

• a) equal to

• b) directly proportional to

• c) inversely proportional to

• d) independent of

When there is a reduction in amplitude over every cycle of vibration, then the body is said to have

• a) free vibration

• b) forced vibration

• c) damped vibration

• d) under damped vibration

In vibration isolation system, if ω/ωn < 2, then for all values of damping factor, the transmissibility will be

• a) less than unity

• b) equal to unity

• c) greater than unity

• d) zero

The first critical speed of an automobile running on a sinusoidal road is calculated by (modeling it as a single degree of freedom system)

• a) Resonance

• b) Approximation

• c) Superposition

• d) Rayleigh quotient