[填空题]
A 75-cm-long guitar string of mass 2.10 g is near a tub 9xs :qvkvbdt85;pr:ne thatmgoy7g:q8g*j lk/axg/ c6m:a /axs b; is open at one end and also 75 cm long. How b ggxoc:/k*:s8a/ x67;/j malqyaggmmuch tension should be in the string if it is to produce resonance (in its fundamental mode) with the third harmonic in the tube? $ \times10^{ 2}$ N
