Compare with a standard wave equation,
$y=a \sin \left(\frac{2 \pi x}{\lambda}-\frac{2 \pi t}{T}+\phi\right)$
we get $\frac{2 \pi}{\lambda}=0.5 \pi$ or, $\lambda=\frac{2 \pi}{0.5 \pi}=4 \mathrm{m}$
$\frac{2 \pi}{T}=4 \pi$ or $, T=\frac{2 \pi}{4 \pi}=\frac{1}{2} \sec$
$v=1 / T=2 \mathrm{Hz}$
Wave velocity, $v=\lambda v=4 \times 2=8 \mathrm{m} / \mathrm{sec}$
If the distances are expressed in cms and time in seconds, then the wave velocity will be ...... $cm/sec$
