An open pipe of sufficient length is dipping in water with a speed v vertically. If at any instant l is lengths of tube avoce water. Then the rate at which fundamental frequency of pipe changes , is ( speed of sound = c)

Options

A. `cv//2I^(2)`
B. `cv//4I^(2)`
C. `c//2v^(2)I^(2)`
D. `c//4v^(2)I^(2)`

Answer

B

Explanation

`f=(c)/(4l)`
`|(df)/(dt)|=(c)/(4I^(2))|(dl)/(dt)|=(cv)/(4l^(2))`