[填空题]
When you slosh the wa4 *isemh9 tn)q-w+cpouw p(3xter back and forth in a tub at just the right 063ka umhhx0a frequency, the water alternately rises and falls at each end, remaining relatively calm at the center. Suppose the frequency to produce such a standing wave in a 65-cm-wide tub is 0.85 Hz. What is the s06kua xa3m h0hpeed of the water wave? m/s