Question

If the velocity of sound in air is 336m/s,the maximum length of a closed pipe that would produce just audible sound is

Answer 1

$n = v \div 4l$
as n = 20Hz
therefore
$l = v \div 4n$
therefore
$336 \div 4 \times 20 = 4.2m$
therefore the maximum length of a closed pipe that would produce just audible sound is 4.2m