1. The problem statement, all variables and given/known data A 1.0m long vertical tube is filled with water. A tuning fork vibrating at 580Hz is held over the open top of the tube as the water is slowly drained from the bottom. At what water heights, measured from the bottom of the tube, will there be a standing wave in the tube? Speed of sound in air =340m/s 2. Relevant equations For an open-open tube: fn=n*v/2*L For an open-closed tube: fn=n*v/4*L 3. The attempt at a solution I don't know if this is an open open or an open closed tube... What I have done is : If there was no water, its open open, then fundamental frequency is fn=340/2=170Hz Now we drain water, it becomes open-closed and we want to find the lenght of the tube which remains with no water in it AT THE MOMENT there is a standing waves. So L(prime)=V/4fn, fn is the one calculated before. L(prime)= 0.5m But I don't know if i can re use fn as I did orI am correct in all that! Please help me !!! Thank you.