[问答题]
A string can have a “free” end if thatmqvccacu 8 +/5nr3 (cr end is /p8n1/le ke cpattached to a ring that can slide without friction on a vertical pole (Fig. 11–57). Determine the wavelengths of the resonant vibrations of such a string with one end fixed and the othep c1n e//8kpler free.