Question

In a rope the tension is established according to the figure. The observed wave speed is v = 24.0 m / s when the suspended mass is m = 10.0 kg. (a) What is the wave speed when the suspended mass is m = 8.0 kg?

a 67.2 m/s

b 4.4 m/s

c 21.47 m/s

d 26.8 m/s

e none

Answer 1

Wave speed is given by:

V =

T = tension in the rope = m*g

= mass per unit length for rope

Since mass per unit length will remain constant for given length, So wave speed is directly proportional to the square root of mass, which means

V2/V1 =

V2 = V1*

Using given values,

when m1 = 10.0 kg, then V1 = 24.0 m/sec

So when m = 8.0 kg

V2 = 24*

V2 = 24*sqrt 0.8

V2 = 21.5 m/sec = wave speed when suspended mass is 8.0 kg

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