A wire stretched between two rigid supports vibrates in its fundamental mode with a frequency of $45\…

A wire stretched between two rigid supports vibrates in its fundamental mode with a frequency of $45\ \mathrm{Hz}$. The mass of the wire is $3.5\times10^{-2}\ \mathrm{kg}$ and its linear mass density is $4\times10^{-2}\ \mathrm{kg\,m^{-1}}$. What is the speed of transverse wave on string and tension in the wire?

Solution

Sol. Length of wire = $\dfrac{\text{Mass of wire}}{\text{Linear density}} = \dfrac{3.5\times10^{-2}}{4\times10^{-2}} = 0.875\ \mathrm{m}$ Now, $f = \dfrac{1}{2l}\sqrt{\dfrac{T}{\alpha}}$ $\therefore$ Tension in the wire, $T = 4f^{2}l^{2}\alpha$ $\qquad = 4(45)^{2}(0.875)^{2}(4\times10^{-2}) = 248.1\ \mathrm{N}$ Speed of transverse wave, $v = f\lambda = f(2l)$ $\qquad = 45\times 2\times 0.875 = 78.75\ \mathrm{ms}^{-1}$ Answer: $78.75\ \mathrm{ms}^{-1}$

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