In a cylindrical pipe with length L and radius R, water is flowing at a constant velocity u. The total momentum of the water flowing through the cylinder, denoted P, is given by P := p X Li X V, where p = 0.9971(3'5/1'113 is the density of water and V = ERZL is the volume of the cylinder. However, a general pipe need not be a cylinder since the radius R can change as you go along the length. That is, if x indicates how far along the pipe you are, R = R(x). Due to a principal called conservation of mass, the velocity of the water must change if the Is the v0Iume or tne cylinder. However, a general pipe need not be a cylinder since the radius R can change as you go along the length. That is, if x indicates how far along the pipe you are, R = R(x). Due to a principal called conservation of mass, the velocity of the water must change if the radius changes. C-D l|I%>