STUPIDSID
1(a)
What is beat phenomena?
2 M
1(b)
Distinguish between longitudinal, transverse and torsional vibration.
2 M
1(c)
A harmonic motion is given by equation x=5Sin(4t+Φ).Find its two components, one that leads it by 30° and other that lags it by 80°.
3 M
Solve any one question from Q.1(d) & Q.1(e)
1(d)
The sphere of diameter D floats half submerged in water.If the sphere is depressed slighted and released, determine the period of vibration. What is the time period if D-1m.
7 M
1(e)
A spring mass system with mass m and stiffness k has a natural frequency of f. Determine the value of stiffness k' of another spring which when,
i) Connected in series with spring k, will lower the natural frequency by 20%
ii) Connected in parallel with spring k, will raise the natural frequency by 20%
i) Connected in series with spring k, will lower the natural frequency by 20%
ii) Connected in parallel with spring k, will raise the natural frequency by 20%
7 M
2(a)
Define over damped and under damped system.
2 M
2(b)
What do you understand by dry friction damping?
2 M
2(c)
Define terms 'Damped Natural Frequency' and 'Critical Damping Coefficient'.
3 M
Solve any one question from Q.2(d) & Q.2(e)
2(d)
A thin plate of area A and weight W is attached to the end of the spring and allowed to oscillate in a viscous fluid as shown in Figure. If f1 is the frequency of system in air and f2 is frequency in viscous liquid, show that:
\[ \displaystyle \alpha =\dfrac{2\pi W\sqrt{(f_{1}^{2}-f_{2}^{2})}}{gA}\].
Where the damping force on the plate is, Fd=2αAV
2A being the total surface on the plate and V its velocity.
:!mage
\[ \displaystyle \alpha =\dfrac{2\pi W\sqrt{(f_{1}^{2}-f_{2}^{2})}}{gA}\].
Where the damping force on the plate is, Fd=2αAV
2A being the total surface on the plate and V its velocity.
:!mage
7 M
2(e)
A vibratory system is defined by following parameters:
m=3 kg, K=100N/m, C=3 N-sec/m
Determine
i) Damping factor
ii) Damped natural frequency
iii) Logarithmic decrement
iv) Ratio of two consecutive amplitudes.
m=3 kg, K=100N/m, C=3 N-sec/m
Determine
i) Damping factor
ii) Damped natural frequency
iii) Logarithmic decrement
iv) Ratio of two consecutive amplitudes.
7 M
3(a)
Define
i) Magnification factor
ii) Transmissibility Ratio
i) Magnification factor
ii) Transmissibility Ratio
2 M
3(b)
What do you understand by whipping speed?
2 M
3(c)
What is meant by vibration isolation?
3 M
Solve any one question from Q.3(d) & Q.3(e)
3(d)
A system of beam supports a mass of 1200kg. The motor has unbalanced mass of 1 kg located at 6.0 cm radius. It is known that resonance occurs at 2210rpm. What amplitude of vibration can be expected at the motor's operating speed of 1440 rpm, if damping factor is assumed to be less than 0.10.
7 M
3(e)
A disc of mass 4kg is mounted midway between bearings which may be assumed to be simple supports. The bearings span is 48mm. The steel shaft which is horizontal is 9mm in diameter. The CG of the disc is displaced 3mm from the geometric centre. The equivalent viscous damping at the centre of the disc shaft may be taken as 49 N-sec/m. If the shaft rotates at 760 rpm, find the maximum stress in the shaft and compare it with dead load stress in the shaft. Also find the power required to drive the shaft at this speed.
7 M
4(a)
Define Node point and mode shape.
2 M
4(b)
What do you understand by principle modes of vibration?
2 M
4(c)
Derive an expression to determine length of torsion-ally equivalent shaft.
3 M
Solve any one question from Q.4(d) & Q.4(e)
4(d)
Determine the natural frequencies for the system shown in fig-2. Assume:
k1=1000N/m, k2=500N/m, m1=50kg, m2=10kg.
:!mage.
k1=1000N/m, k2=500N/m, m1=50kg, m2=10kg.
:!mage.
7 M
4(e)
Explain the principle of dynamic vibration absorb er. What is a tuned absorb er?
7 M
5(a)
What is meant by term 'Sound Spectra'?
2 M
5(b)
What do you understand by term 'Weighting Networks'?
2 M
5(c)
Show that when the distance from point of source is doubles the sound intensity level decreases by 6dB.
3 M
Solve any one question from Q.5(d) & Q.5(e)
5(d)
Explain the noise exposure limits for persons working in industry recommended by OSHA.
7 M
5(e)
Write a short note on Noise control techniques.
7 M
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