A steel wire with mass per unit length 7 . 0 × 10 ^ – 3 kg m ^ – 1...

The formula to calculate the speed $\left(v\right)$ of the transverse wave generated in a stretched string is given by

$v = \sqrt{\dfrac{T}{\mu}} . . . . . . . . . . . . . . . . . . . . . . . . . . . . ( 1 )$

where, $T$ is the tension in the string and $\mu$ is the mass density.

Therefore, required speed of the wave:

$\begin{cases}v & = & \sqrt{\dfrac{70N}{7 \times {10}^{- 3}kg{m}^{- 1}}} \\ & = & 100m / s\end{cases}$