A guitar string of length L $=0\mathrm{.}94$ m is oriented along the x$-$direction and under a tension of T $=81$ N$.$ The string is made of steel which has a density of $=7800$ kg $/$ m$3.$ The radius of the string is r $=8\mathrm{.}1$ x $10-4$ m$.$

A transverse wave of amplitude A $=0\mathrm{.}0020$ m is formed on the string. Calculate the mass per unit length of the guitar string in kg$/$m$.$

Calculate the velocity $($in m$/$s$)$ of a traveling transverse wave on the guitar string.