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Absolute and Gauge Pressure

A dam to create a large fresh water lake is constructed. It will be approximately 14 meters deep. A horizontal pipe 1.2 meters long and 4 cm in diameter will pass through the dam at a depth of 7 meters to allow for release of the water in emergencies and for sampling. In normal situations, a plug will secure the pipe opening.


Pls explain the calculations in detail.

(a) What will be the total force on the left side of the plug?
F(left) = ____________________ N

(b) What is the total force on the right side of the plug?
F(right) = ____________________ N

(c) What is the gauge pressure on the plug?
Pgauge = ____________________ Pa

(d) If the plug were to be removed, how much water would flow out in 3 hours?
¦¤VOL = ____________________ m3


Solution Preview

Diameter of the pipe = 4 cm
Radius of the pipe = 2 cm or 0.02 m
Area of cross section of pipe = 3.14*0.02*.02
= 1.256*10^-3 m^2

(a) Hydrstatic pressure at a depth of 7 m = hdg
= 7*1000*9.8
= 6.86*10^4 N/m^2 or Pascal (Pa)
Total pressure = hydrostatic + atmospheric preuure
= 6.86*10^4 + 1.01*10^5
= 1.696*10^5 Pa
Pressure = Thrust / Area
Thrust or force acting normally on the left side of the plug = Pressure*Area

Solution Summary

Liquid Pressure = hdg