Answer:
[tex]v = 1523.3 m/s[/tex]
Explanation:
For two guitars we have the situation given here
First guitar is in 5th harmonic
so we have
[tex]5 \frac{\lambda}{2} = 2.17 m[/tex]
[tex]\lambda_1 = 0.868 m[/tex]
now we have
[tex]f_1 = \frac{v}{\lambda_1}[/tex]
now for second guitar we have
[tex]4 \frac{\lambda}{2} = 2.17[/tex]
[tex]\lambda_2 = 1.085 m[/tex]
now for second guitar we have
[tex]f_2 = \frac{v}{\lambda_2}[/tex]
now we know that
[tex]f_1 - f_2 = f_{beat}[/tex]
[tex]\frac{v}{0.868} - \frac{v}{1.085} = 351[/tex]
[tex]v(0.23) = 351 [/tex]
[tex]v = 1523.3 m/s[/tex]