Wave Mechanics Vibration Of String Question 41

Question: A steel rod 100 cm long is clamped at its mid-point. The funda-mental frequency of longitudinal vibrations of the rod is given to be 2.53 kHz. What is the speed of sound in steel

[AFMC 2000]

Options:

A) 5.06 km/s

B) 6.06 km/s

C) 7.06 km/s

D) 8.06 km/s

Show Answer

Answer:

Correct Answer: A

Solution:

If a rod clamped at middle, then it vibrates with similar fashion as open organ pipe vibrates as shown.

Hence, fundamental frequency of vibrating rod is given by $ n _{1}=\frac{v}{2l} $

Therefore $ 2.53=\frac{v}{4\times 1} $

Therefore v = 5.06 km/sec.