Is P0 always equal to 1 atm?

[mrh125]

even if you change the medium? I'm very curious about this p=ρgh so you'd think that if something was on the surface of liquid mercury which has a different density than water you'd think p0 would have a different value.

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[Cmdr_Shepard]

I'm confused about your question. If you're looking at something at the surface, then what value are you putting in for "h" in your equation?

 

[mrh125]

I'm confused about your question. If you're looking at something at the surface, then what value are you putting in for "h" in your equation?

good point, h would be zero, but im wondering if the different density would change p0 at all? based off of what you're saying P=p0+pg(0), so P=p0=1atm so the answer would be no.

 

[Cmdr_Shepard]

Correct.

That's some damn fine reasoning skills you got there. 😛

 

[mrh125]

Correct.

That's some damn fine reasoning skills you got there. 😛

lol thanks for the help 🙂 =p. my reasoning skills often cause me to overthink stuff like this though =/.

 

[Cmdr_Shepard]

Yeah I hear you. The MCAT is kind of weird that way. Underthinking = bad, overthinking = bad. You need to find the Goldilocks level of thinking.

 

[Odi]

P=p0+pg(0), so P=p0=1atm

I got a question wrong yesterday because of this mode of thinking.

I was basically asked what is not always true about the pressure on the surface of the liquid?

Answer: P0 = 1 atm.

Reasoning is that P0=Patm ...and it's not always the case that Patm = 1atm. That's only under standard conditions.

If you go higher in elevation where the air is less dense, then P0 < 1atm. P0 doesn't depend on any property of the medium itself--it's the pressure exerted from the fluid (in most cases--air) on top of the medium.

 

[Cmdr_Shepard]

Yeah, everything I said is assuming you're at sea level.

 

[Iatro]

You are standing on a rock. Now you are standing on cement. Your height didnt change. Did Po change? :O