An open vertical tube has water in it. A tuning fork vibrates over its mouth. As the water level is lowered in the tube, a resonance is heard when the water level is 64.75 cm below the top of the tube, and again after the water level is 68.25 cm below the top of the tube a resonance is heard. What is the frequency of the tuning fork? The speed of sound in air is 343 m/s. Answer in units of Hz How many nodes are in the tube after the water has reached the second distance from the top of the tube?