Question

A $5.5$ metre length of string has a mass of $0.035 \,kg$. If the tension in the string in $77\, N$, the speed of a wave on the string is

• A. $110\,ms^{-1}$
• B. $165\,ms^{-1}$
• C. $77\,ms^{-1}$
• D. $102\,ms^{-1}$

Answer 1

Answer: (A)

$110\,ms^{-1}$

Answer 2

$\mu=\frac{0.035}{5.5}kg/ m$, $T=77\,N$
where $\mu$ is mass per unit length.
$v=\sqrt{\frac{T}{\mu}}=\sqrt{\frac{77\,\times \,5.5}{0.035}}=110\, m/s^{-1}$