Water enters through end A with a speed 0, and leaves through end B with a speed u2 of a cylindrical tube AB. The tube is always completely filled with water. In case I the tube is horizontal, in case II it is vertical with the end A upward and in case III it is vertical with the end B upward. We have v1 = v2 for
(a) case I
(b) case II
(c) case III
(d) each case.
