In a resonance-tube containing air, the source of sound is a small loudspeaker driven by a variable-frequency oscillator. The distance between successive antinodes is 10 cm for a frequency of 1625 Hz. When the frequency is slowly reduced, the standing wave pattern at first collapses and then reapears at a frequency of 1600 Hz. (a) Find the speed of the sound in air. (b) Find the distance between successive antinodes when the frequency is 1600 Hz. (c) Estimate the vibrating length of the tube, if the loudspeaker is close to a displacement node. (d) If the frequency is further reduced, at what frequency will the next pattern be obtained?