3.8. Example. Incompressible liquid of constant density p is contained within a region bounded by two concentric rigid spherical surfaces of radii a, b (a< b). The fluid is initially at rest. If the inner boundary is suddenly given a velocity Uk, where k is a constant vector, show that the outer surface experiences the impulsive force 2mpUla b b-a b'-a Also calculate the corresponding K.E. generated by the impulsive motion.