Three resonant frequencies of string are 90, 150 and 210 Hz. If the length of the string is 80 cm, what is the speed of the transverse waves in the string ?

The fundamental frequency of the string = H.C.F of resonant frequencies

    i.e.                            frequency(n)    = 30 Hz

 Now by the formula

                                             n = v/2l    (l = .8m)

                                             v = n x 2l

                                                = 30 x 2x.8

                                                = 48m/s

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