For an incompressible flow, this quantity dot del times u equals 0 according to the Taylor-Proudman theorem. When kinetic energy is constant, this quantity traces out the polhode on Poinsot’s ellipsoid. This quantity’s time derivative is proportional to the strength of the Euler force. The time derivative of one component of this quantity and the product of the other two components of it appear on one side of Euler’s (*) rigid body equations. Negative 2 m times this quantity cross r gives the strength of the Coriolis force. Reference frames with a non-zero value of this quantity experience the fictitious centrifugal force. The product of this quantity and the moment of inertia equals angular (-5[1])momentum. For 10 points, name (10[1])this vector quantity with units of radians per second. (10[3])■END■