Pressure above & below the surface of a lake.

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Homework Help Overview

The discussion revolves around calculating pressure changes in a freshwater lake, specifically focusing on the pressure increase when descending below the surface and the pressure decrease when ascending above it. The problem involves understanding the relationship between pressure, depth, and atmospheric conditions.

Discussion Character

  • Conceptual clarification, Assumption checking

Approaches and Questions Raised

  • Participants explore the equation for pressure changes, questioning whether atmospheric pressure should be included in calculations. There is discussion about the correct formulation of the pressure equation, particularly in relation to depth and atmospheric pressure.

Discussion Status

Some participants have provided insights regarding the equation to use, with one suggesting that the atmospheric pressure may not need to be included when calculating pressure increases. There appears to be a productive exchange of ideas, though no consensus has been explicitly stated.

Contextual Notes

Participants are navigating the specifics of the problem, including the implications of atmospheric pressure on calculations and the conditions under which certain equations apply. There is mention of the density of air, which may influence the discussion but is not fully explored.

thedark_master
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At the surface of a freshwater lake the pressure is 106 kPa. (a) What is the pressure increase in going 35.1 m below the surface? (b) What is the approximate pressure decrease in going 34 m above the surface? Air at 20°C has density of 1.2 kg/m3.

i was almost sure that i needed to use this equation: P=P(atm)+ pgd but for some reason it is saying that it is wrong
please help
 
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thedark_master said:
At the surface of a freshwater lake the pressure is 106 kPa. (a) What is the pressure increase in going 35.1 m below the surface? (b) What is the approximate pressure decrease in going 34 m above the surface? Air at 20°C has density of 1.2 kg/m3.

i was almost sure that i needed to use this equation: P=P(atm)+ pgd but for some reason it is saying that it is wrong
please help

If it is demanded the pressure increase, you don´t have to add the atmospheric pressure.
 
so you are sayng that it is P=pgd?
 
omg that is the right answer, thank you
 

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