In the transonic regime, two objects with the same longitudinal area distribution have the same value for this quantity according to a rule named for Whitcomb. Prandtl introduced the boundary layer to explain a situation in which this quantity drops to zero for an inviscid, incompressible flow at constant velocity, called d’Alembert’s (“dah-lom-BAIRʼs”) paradox. For a sphere in at low Reynolds number flow, this quantity equals (read slowly) “six pi times (10[3])dynamic viscosity times radius times flow velocity” according to (10[1]-5[1])Stokes’ law. When this force equals gravity for a falling object, the object has (10[1])reached terminal velocity. For 10 points, name this force that opposes the movement of an (10[1]-5[1])object moving through a (10[1])fluid. ■END■