[填空题]
A tuning fork is set into vjomt, 9y9 /p 1o5brtd):g qoxqk *xx;y9.- n47ktdr2m yqpojhibration above a vertical open tube filled with water (Fig. 12–35). The water level is allowed to drop slowly. As it does so, the air in the tube above the water level is heard to resonate with the tuning fork when the distance from the tube opening to the water level is 0.125 m and again attjpnyd2.qmo k9 h4 r-7 0.395 m. What is the frequency of the tuning fork? Hz
