Question

Two open pipes of length 20 cm and 20.1 cm produces 10 beats/s. The velocity of sound in the gas is

• A. 804 m/s
• B. 402 m/s
• C. 420 m/s
• D. 330 m/s

Answer 1

Answer: (A)

804 m/s

For open pipes, $f=\frac{v}{2l}$

$\therefore f_1-f_2=\frac{v}{2}(\frac{1}{l_1}-\frac{1}{l_2})$

$\Rightarrow v=\frac{2\left(10\right)\times l_1{l}_2}{(l_2-l_1)}$

$=\frac{20\times 20\times 20.1\times {10}^{-2}}{0.1}$

$=804m{s}^{-1}$