• # question_answer If the stream function is given by $\psi =3xy,$ then the velocity at a point (2, 3) will be: A) 7.21 unit                       B) 10.82 unitC) 18 unit             D) 54 unit

$\psi =3xy$ $u=\frac{\delta \psi }{\delta y}=3x,$ $v-\frac{\delta \psi }{\partial }=-\,3y$ Resultant velocity, $v=\sqrt{{{u}^{2}}+{{v}^{2}}}=\sqrt{9{{x}^{2}}+9{{y}^{2}}}$