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 (-5[1])Poinsot’s (-5[1])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 (-5[1])on one side of Euler’s (*) rigid body equations. Negative 2 m times this quantity cross r gives the strength of the (10[1])Coriolis (10[1]-5[1])force. Reference frames with a non-zero (-5[1])value of (10[1])this (-5[1])quantity experience the (-5[2])fictitious (-5[1])centrifugal force. The product of this quantity and the moment of inertia equals angular (-5[3])momentum. For (10[1])10 points, name (10[1])this vector quantity with units of radians per (10[1])second. (10[12]0[6])■END■