Q 11-14-042JEE MainJEE Main 2024 (27 Jan, Shift 2)Medium
A closed organ pipe $150\ \text{cm}$ long gives 7 beats per second with an open organ pipe of length $350\ \text{cm}$, both vibrating in fundamental mode. The velocity of sound is ______ $\text{m s}^{-1}$.
Numerical value type. Enter your answer.
Answer: 294
$$f_{closed} = \frac{v}{4\times1.5} = \frac v6,\qquad f_{open} = \frac{v}{2\times3.5} = \frac v7$$
$$\frac v6 - \frac v7 = 7 \;\Rightarrow\; \frac{v}{42} = 7 \;\Rightarrow\; v = 294\ \text{m s}^{-1}$$
Solution by Sreeraj P, M.Sc Physics