Question

The velocity of sound in a gas, in which two wavelengths, 4.08 m and 4.16 m produce 40 beats in 12 s, will be:

• A. 282.8 ms-1
• B. 175.5 ms-1
• C. 353.6 ms-1
• D. 707.2 ms-1

Answer 1

Answer: (D)

707.2 ms-1

Answer 2

The correct answer is (D) : 707.2 ms–1
Beat Frequency = f1 - f2.
$\frac{v}{4.08} - \frac{v}{4.16} = \frac{40}{12}$
$v = \frac{40}{12} × \frac{4.08 × 4.16 }{ 0.08}$
= 707.2 m/s