How Does Water Pressure Change with Depth and Altitude?

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SUMMARY

The discussion focuses on calculating pressure changes in water due to depth and altitude variations. The initial pressure at the surface of a freshwater lake is 106 kPa. For a depth of 34.5 meters, the pressure increase is calculated using the formula ΔP = ρgΔh, resulting in a total pressure of 439.4 kPa. The pressure decrease when moving 36 meters above the surface must also be determined using atmospheric pressure considerations.

PREREQUISITES
  • Understanding of fluid mechanics principles
  • Familiarity with pressure equations, specifically Ph20 = pgh and Pabs = Ph20 + Patm
  • Knowledge of density and gravitational acceleration
  • Basic algebra for solving equations
NEXT STEPS
  • Research the derivation and application of the hydrostatic pressure equation
  • Learn about atmospheric pressure variations and their effects on fluid systems
  • Explore the concept of buoyancy and its relation to pressure changes
  • Study real-world applications of pressure calculations in engineering and environmental science
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Students studying physics, particularly those focusing on fluid mechanics, as well as educators and professionals involved in environmental science and engineering disciplines.

Devin Longo
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Homework Statement


At the surface of a freshwater lake the pressure is 106 kPa. (a) What is the pressure increase in going 34.5 m below the surface? (b) What is the approximate pressure decrease in going 36 m above the surface? Air at 20°C has density of 1.2 kg/m3.


Homework Equations


Ph20 = pgh
Pabs = Ph20 + Patm




The Attempt at a Solution



I calculated both equations and got 439.4 kPa. I then subtracted 106 from 439.4 to get number one, but it doesn't work! How can I calculate number one? Also, I don't know where to begin for 2!
 
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The pressure change in both cases can be calculated via ΔP = ρgΔh.
 

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