a. Derive an expression for the torsionally equivalent shaft.

(2)
b. Describe Dunkerley’s method to find the natural frequency of a shaft
carrying
several loads. (4)

c. Describe various methods for controlling vibrations in a vibrating system.

(2)

XI. 1) Explain the working principle of a seismometer with a neat sketch.
(4) 2) Two rotors A and B are attached to the ends of a shaft of length 0.5m.
The rotor A weigh 300N and its radius of gyration is 0.3m and the
corresponding values for rotor
B are 500 N and 0.5m respectively. The shaft is 0.1m in diameter for the first 0.3m
,0.15m for the next 0.1m and 0.12 m for the remainder of its length. The value of
modules of rigidity for the shaft material is 0.85x 1011 N/m2. Find i) Position of
the node ii) frequency of torsional vibration.

XII.