$\frac{3}{2} \lambda=\ell ; \mathrm{f}=\frac{\mathrm{v}}{\ell} ; \lambda=\frac{2 \ell}{3} ; \mathrm{v}=\mathrm{f} \lambda$
$v=300 \times \frac{2}{3} \times 1=200 \mathrm{m} / \mathrm{s}$
$y(x,t)\, = \,0.6\,\sin \,\left( {\frac{{2\pi }}{3}x} \right)\,\cos \,(120\,\pi t)$
where $x$ and $y$ are in $metre$ and $t$ in $second$ . The length of the string is $1.5\,m$ and its mass is $3.0\times 10^{-2}\,kg$ the tension in the string will be .... $N$
$(i)$ The source may be moving towards the observer with a velocity of $30\,ms^{-1}$
$(ii)$ The source may be moving towards the observer with a velocity of $33\,ms^{-1}$
$(iii)$ The observer may be moving towards the source with a velocity of $30\,ms^{-1}$
$(iv)$ The observer may be moving towards the source with a velocity of $33\,ms^{-1}$