$3-6.$ A two$-$dimensional flow field for a benzene can be described by

$V=\{(6y^2-x)i+(2x+y)j\}\frac{m}{s},$ where $x$ and $y$ are in meters. Determine the

magnitude of the velocity of a particle located at $(2m,-1m),$ and its direction

measured counterclockwise from the positive $x$ axis.

$3-10.$ A balloon is released into the air from the origin and carried along by the

wind, which blows at a constant rate of $u=0\mathrm{.}5\frac{m}{s}.$ Also, buoyancy and thermal

winds cause the balloon to rise at a rate of $v=(0\mathrm{.}8+0\mathrm{.}6y)\frac{m}{s},$ where $y$ is in

meters. Determine the equation of the streamline for the balloon, and draw this

streamline.