physics
posted by andrew .
Tension is maintained in a string. The observed wave speed is 21 m/s when the suspended mass is 3.0 kg.
a) What is the mass per unit length of the string? (in kg/m)
b) What is the wave speed when the suspended mass is 1.6 kg? (in m/s)

(a)
Velocity in the stretched string is
v = sqrt(T/mₒ),
T = m•g,
v = sqrt(m•g/mₒ),
mₒ =m•g/v² = 3•9.8/21² = 0.067 kg/m.
(b)
v1 = sqrt(T1/mₒ) = sqrt(m1•g/mₒ) =
= sqrt(1.6•9.8/ 0.067)= 15.3 m/s.