
Which one of the following correctly shows the direction of the velocity of the points $1, 2$ and $3$ on the string
$y\left( {x,t} \right) = 2\,\sin \,\left( {\frac{{2\pi }}{3}x} \right)\,\cos \,\left( {100\,\pi t} \right)$
where $x$ and $y$ are in $cm$ and $t$ is in $s$. Which of the following statements is correct ?