GATE ME 2014 | Vibrations Question 28 | Theory of Machines

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GATE ME 2014

MCQ (Single Correct Answer)

-0.3

In vibration isolation, which one of the following statements is NOT correct regarding Transmissibility ($$T$$)?

$$T$$ is nearly unity at small excitation frequencies

$$T$$ can be always reduced by using higher damping at any excitation frequency

$$T$$ is unity at the frequency ratio of $$\sqrt 2 $$

$$T$$ is infinity at resonance for undamped systems

GATE ME 2013

MCQ (Single Correct Answer)

-0.3

If two nodes are observed at a frequency of $$1800$$ rpm during whirling of a simply supported long slender rotating shaft, the first critical speed of the shaft in rpm is

$$200$$

$$450$$

$$600$$

$$900$$

GATE ME 2010

MCQ (Single Correct Answer)

-0.3

The natural frequency of a spring-mass system on earth is $${\omega _n}.$$ The natural frequency of this system on the moon (g_moon = g_earth/6) is

$${\omega _n}$$

$$0.408$$$${\omega _n}$$

$$0.204$$$${\omega _n}$$

$$0.167$$$${\omega _n}.$$

GATE ME 2009

MCQ (Single Correct Answer)

-0.3

The rotor shaft of a large electric motor supported between short bearings at both the ends shows a deflection of $$1.8$$ mm in the middle of the rotor. Assuming the rotor to be perfectly balanced and supported at knife edges at both the ends, the likely critical speed (in rpm) of the shaft is

$$350$$

$$705$$

$$2810$$

$$4430$$

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