[问答题]
A string can have a “free” end if thazthp3. :9sjnde)-q fmt end is attached to a ri/tm)ch2 xj zzgr)6 9ubng that can slide without friction on a vertical pole (Fig. 11–57). Determine)c g9/2tbzhux6j z m)r the wavelengths of the resonant vibrations of such a string with one end fixed and the other free.