A string of length L and mass M hangs freely from a fixed point. Then the velocity of transverse waves along the string at a distance x from the free end is
The velocity of transverse waves along a stretched string depends on the tension in the string. The tension at a distance x from the free end is given by T = Mgx/L. Therefore, the velocity v = sqrt(T/μ) = sqrt(gx), where μ is the mass per unit length of the string.