What is the gauge pressure
inside the bottom of the tank due
to the weight of the water alone?
What is the absolute pressure,
including atmospheric pressure,
pressing down inside the
bottom?
PH2O = ȡgh
PH2O = 2400 Pa
Pabs = 2400 Pa + 101,300 Pa
Pabs = 103,700 Pa
13.5 - Sample problem: pressure at the bottom of a lake
Variables
Strategy
- The atmospheric pressure is given. Find the gauge pressure of the water in the lake.
- Add the atmospheric and gauge pressures to get the absolute pressure.
Physics principles and equations
The gauge pressure of the water at the bottom of the lake is
PH2O = ȡgh
The absolute pressure at the bottom of the lake is
Pabs = PH2O + Patm
This lake is at sea level. What is the
absolute pressure at the bottom of the
lake?
absolute pressure Pabs
atmospheric pressure Patm = 1.013×10^5 Pa
gauge pressure due to water PH2O
density of water ȡ = 1000 kg/m^3
acceleration of gravity g = 9.80 m/s^2
height of water column h = 50.0 m