Thermodynamics question?

Question

This is all new to me and my book is no help. This is a homework problem."Determine the differnce in pressure, in lbf/in^2 between the top and the bottom of a 6 ft diameter sewer pipe filled with water. Assume the density of water is 62.2 lb/ft^3 and g=32.2ft/s^2." How is this solved? please explain the steps for solving

Answer 1

The difference is merely the weight of the water (because the same hydraulic pressure exists top and bottom) so
6' of water at 62.2 #/ft per sq.ft, means 373.2 #/sq.ft so divide by
144 sq.in/sq.ft gives 2.592 #/sq.in or psi.

Answer 2

Not really a thermo problem more of a hydrostatics problem.

Water weighs 62.2 lbs/cubic foot. So it exerts 62.2 lbs/ square ft pressures (force/unit area) for every ft of height.

So the difference in pressure is 6 x 62.2 = lbs/ ft^2

There are 12^2 (144) square inches per square ft

So the answer in the units requested is 6 x 62.2 / 144

gravitational acceleration (g) is not needed to solve the problem as pounds is a force unit.

Answer 3

pressure= depth of water * density of water *g