The two-dimensional velocity field for an incompressible newtonian fluid is described by the relationship v = (12xy2 − 6x 3 )i + (18x 2 y − 4y 3 )j where the velocity has units of m/s when x and y are in meters. determine the stresses σxx, σyy, and τxy at the point x = 0.5 m, y = 1.0 m if pressure at this point is 6 kpa and the fluid is glycerin at 20 °c.