3.4 (a) What pressure gradient along the streamline, dp/ds, is required to accelerate water upward in a vertical pipe at a rate of 45 ft/s2? (b) What is the answer if the flow is downward? 3.4 (a) What pressure gradient along the streamline, dp/ds, is required to accelerate water upward in a vertical pipe at a rate of 45 ft/s2? (b) What is the answer if the flow is downward