6.13 Water flows in a pipeline. At a point in the line where the diameter is 7 in., the velocity is 12 fps and the pressure is 50 psi. At a point 40 ft away the diameter reduces to 3 in. Calculate the pressure here when the pipe is

(a) horizontal,

(b) vertical with flow downward, and

(c) vertical with the flow upward. Explain why there is a difference in the pressure for the different situations.