Answer
The rope must have a tension of 43.2 N
Work Step by Step
We can find the required speed of the transverse waves.
$v = \lambda~f$
$v = (0.750~m)(40.0~Hz)$
$v = 30.0~m/s$
We can find the required tension.
$\sqrt{\frac{F_T}{\mu}} = v$
$F_T = v^2~\mu$
$F_T = v^2~(\frac{m}{L})$
$F_T = (30.0~m/s)^2~(\frac{0.120~kg}{2.50~m})$
$F_T = 43.2~N$
The rope must have a tension of 43.2 N
