[填空题]
A 75-cm-long guitar strinx)r 0k6g 6w 0wvyg2fej;2kqafg of mass 2,/)t* klyq*nga w o1g o+/pxbb.10 g is near a tube that is open at one end and also 75 cm long. How much tension should be in the string if it is to produce resonance (in its fundamental m/o*o ,*kxlpwbgytn gqb/ 1+a)ode) with the third harmonic in the tube? $ \times10^{ 2}$ N
