Trouble with a basic fluid force problem

AI Thread Summary
The discussion centers on calculating the pressure on a horizontal surface 4m underwater with an area of 2m^2. The initial calculation mistakenly used the force formula, resulting in 78,400 N, which is incorrect for pressure. The correct approach is to use the pressure formula, P = F/A, leading to a pressure of 39,200 N/m^2. The confusion arose from calculating force instead of pressure, highlighting the importance of understanding the distinction between these two concepts. This clarification emphasizes the need to divide the force by the area to obtain the correct pressure value.
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What is the pressure on a horizontal surface with an area of 2m^2 that is 4m underwater?

I tried to just use the formula: Force= (Density of water)(Area)(Depth)(gravity), plugging in the values Force=(1000kg/m^3)(2m^2)(4m)(9.8m/sec^2) and get 78400 N, when in reality the real answer is supposed to equal 39,200 N/m^2.
 
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I can confirm your answer. Maybe someone forgot a factor of 2?
 
Ahhh nevermind, I have been calculating the FORCE on the plate and not the PRESSURE on the plate which is P=F/A which would explain they I have to divide the force by 2.
 
Oh, good point. It also changes the units.
 

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