Correct Answer - Option 3 : 7.81 unit/s
Concept:
The velocity in-stream function is given as,
\(u = \frac{{ - \partial {\rm{\Psi }}}}{{\partial y}} ,\;\nu = \frac{{\partial {\rm{\Psi }}}}{{\partial x}} \)
Calculation:
Given:
ψ = 5x - 6y, \(u = \frac{{ - \partial {\rm{\Psi }}}}{{\partial y}} =~6,\;\nu = \frac{{\partial {\rm{\Psi }}}}{{\partial x}} =5\)
Resultant velocity
\( = \sqrt {{u^2} + {\nu ^2}} = \sqrt {{6^2} + {5^2}} = 7.81\;m/s\)
