(a) Tension at a point at a distance x from the support is the due to the weight of the cable
T = \(\frac{m(L-x)}{L}g\)
\(\mu\) = \(\frac mL\)
The speed of transverse wave
v = \(\sqrt{\frac{T}{\mu}}\)
v = \(\cfrac{\frac{m(L-x)g}{L}}{\frac mL}\)
v = \(\sqrt{g(L-x)}\)
(b) Time taken to transverse a distance
dt = \(\frac{dx}{\sqrt{g(L-x)}}\)
total time taken t = \(\int\limits_0^L\frac{dx}{\sqrt{g(L-x)}}\)
t = 2\(\sqrt{\frac Lg}\)