A guitar string $0\mathrm{.}650$ m long has a tension of $61\mathrm{.}0$N and a mass per unit length of $3\mathrm{.}00$ g$/$m$.$

$($a$)$ What is the speed of waves on the string when it is plucked?

$($b$)$ What is the string's fundamental frequency of vibration when plucked?