Qs. 2 Standing waves (tubes) An old mining tunnel disappears into a hiliside. Th
ID: 1792097 • Letter: Q
Question
Qs. 2 Standing waves (tubes) An old mining tunnel disappears into a hiliside. The tunnel is fully blocked somewhere inside by rocks from a landslide. Since it is too dangerous to go inside, you decide to try setting up standing-wave resonances inside the tunnel to measure its length. Using your subsonic amplifier and loudspeaker, you find resonances at 4.5 Hz and 6.5 Hz and at no frequencies between these. It is cold inside the tunnel, you estimate the sound speed to be 336 m/s. Based on your measurements, how far is it to the blockage in the tunnel?Explanation / Answer
In cold mine stationary waves are formed
frequency f = nv/(4L)
f1 = 4.5 Hz
f2 = 6.5 Hz
given f1 and f2 are successive frequncies
f1 = nv/(4L)
f2 = (n+2)*V/(4L)
f2 - f1 = 2v/(4L)
6.5 - 4.5 = 2*336/(4*L)
L = 84 m <<<<<<<======ANSWER