# Pressure above & below the surface of a lake.

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

## Answers and Replies

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SGT
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