Length=l=160cm=1.6m
Frequency=85Hz
#1
Fundamental frequency be v
[tex]\\ \sf\bull\longmapsto v=\dfrac{\nu}{2\ell}[/tex]
[tex]\\ \sf\bull\longmapsto v=\dfrac{85}{2(1.6)}[/tex]
[tex]\\ \sf\bull\longmapsto v=\dfrac{85}{3.2}[/tex]
[tex]\\ \sf\bull\longmapsto v=26.6Hz[/tex]
#2
First we have to find wavelength
[tex]\\ \sf\bull\longmapsto \lambda=\dfrac{c}{v}[/tex]
[tex]\\ \sf\bull\longmapsto \lambda=\dfrac{3\times 10^8ms^{-1}}{26.6}[/tex]
[tex]\\ \sf\bull\longmapsto \lambda=0.112\times 10^8m[/tex]
[tex]\\ \sf\bull\longmapsto \lambda=112\times 10^5m[/tex]
[tex]\\ \sf\bull\longmapsto \lambda=1.12\times 10^6m[/tex]
Now..
Velocity be v
[tex]\\ \sf\bull\longmapsto v=f\lambda[/tex]
[tex]\\ \sf\bull\longmapsto v=26.5\times1.12\times 10^6m[/tex]
[tex]\\ \sf\bull\longmapsto v=29.68\times 10^6[/tex]
[tex]\\ \sf\bull\longmapsto v=2.9\times 10^7m/s[/tex]
