Question

Tension is maintained in a string as in Figure P13.49. The observedwave speed is 16 m/s when thesuspended mass is 3.0 kg.

Figure P13.49

(a) What is the mass per unit length of thestring?
kg/m

(b) What is the wave speed when the suspended mass is 2.2 kg?
m/s

Answer 1

given

a) wave speed V = 16m/s

    suspended mass m = 3.0kg

so the tension in the string T = mg

                                          = 3.0*9.8

                                          = 29.4N

the speed of the wave is given by

    V = √T/μ

    or μ = T/V²

             =29.4N/(16m/s)²

            = 0.115 kg/m

b) the wave speed when the mass is 2.2kg is

    V = √T/μ

        = √2.2*9.8 /0.115

       = √187.5

       = 13.7m/s