The stream function for a two-dimensional, nonviscous, incompressible flow field is given by the expression ψ = −2(x − y) where the stream function has the units of ft2/s with x and y in feet. (a) Is the continuity equation satisfied? (b) Is the flow field irrotational? If, so, determine the corresponding velocity potential. (c) Determine the pressure gradient in the horizontal x direction at the point x = 2 ft, y = 2 ft.