Dynamics of Machinery Test Questions - Set 5

1)   In damped free vibrations, which parameters indicate vibrations?

a. Natural frequency
b. Rate of decay of amplitude
c. Both a. and b.
d. None of the above
Answer  Explanation 

ANSWER: Both a. and b.

Explanation:
No explanation is available for this question!


2)   Calculate natural frequency of damped vibration, if damping factor is 0.52 and natural frequency of the system is 30 rad/sec which consists of machine supported on springs and dashpots.

a. 25.62 rad/sec
b. 20.78 rad/sec
c. 14.4 rad/sec
d. 15.33 rad/sec
Answer  Explanation 

ANSWER: 25.62 rad/sec

Explanation:
No explanation is available for this question!


3)   At which frequency ratio, phase angle increases as damping factor increases?

a. When frequency ratio is less than unity
b. When frequency ratio is more than unity
c. When frequency ratio is zero
d. All of the above
Answer  Explanation 

ANSWER: When frequency ratio is less than unity

Explanation:
No explanation is available for this question!


4)   What is the effect of damping on phase angle at resonance frequency?

a. Phase angle increases as damping increases
b. Damping has no effect on phase angle
c. Phase angle increases as damping decreases
d. None of the above
Answer  Explanation 

ANSWER: Damping has no effect on phase angle

Explanation:
No explanation is available for this question!


5)   Calculate damped natural frequency, if a spring mass damper system is subjected to periodic disturbing force of 30 N. Damping coefficient is equal to 0.76 times of critical damping coefficient and undamped natural frequency is 5 rad/sec

a. 3.99 rad/sec
b. 2.13 rad/sec
c. 4.12 rad/sec
d. 3.24 rad/sec
Answer  Explanation 

ANSWER: 3.24 rad/sec

Explanation:
No explanation is available for this question!


6)   Calculate critical speed of a vehicle which moves on a road having sinusoidal profile of wavelength 2.5 m. The mass of the vehicle is 300 kg and natural frequency of its spring suspension system is 8 rad/sec

a. 4.15 m/sec
b. 3.18 m/sec
c. 2.36 m/sec
d. None of the above
Answer  Explanation 

ANSWER: 3.18 m/sec

Explanation:
No explanation is available for this question!


7)   What is meant by node point?

a. The point at which amplitude of vibration is maximum
b. The point at which amplitude of vibration is minimum
c. The point at which amplitude of vibration is zero
d. None of the above
Answer  Explanation 

ANSWER: The point at which amplitude of vibration is zero

Explanation:
No explanation is available for this question!


8)   What is meant by coupled differential equation?

a. The differential equation in which only rectilinear motions exit
b. The differential equation in which only angular motions exit
c. The differential equation in which both rectilinear and angular motions exit
d. None of the above
Answer  Explanation 

ANSWER: The differential equation in which both rectilinear and angular motions exit

Explanation:
No explanation is available for this question!


9)   The motion of a system executing harmonic motion with one natural frequency is known as _______

a. principal mode of vibration
b. natural mode of vibration
c. both a. and b.
d. none of the above
Answer  Explanation 

ANSWER: both a. and b.

Explanation:
No explanation is available for this question!


10)   Which of the following instruments measure amplitude of a vibrating body?

a. Vibrometers
b. Seismometer
c. Both a. and b.
d. None of the above
Answer  Explanation 

ANSWER: Both a. and b.

Explanation:
No explanation is available for this question!