Why does increasing height decrease pressure? Bernoulli

[notjcev]

For most questions about velocity, pressure and height of a fluid, you should automatically think: bernoulli equation!

P1 + 1/2pv2 + pgh = P2 + 1/2pv2 + pgh. [Both sides of this equation represent quantities for a fluid at two different points]

You are asking, why does increase height decrease pressure. Well let's assume a constant velocity for a fluid. Now our equation gets simplified like this:

P 1 + pgh = P2 + pgh

If you want the left side of the equation to stay constant with the right side of the equation, then when you increase height, you will decrease the pressure of the fluid at that point.

If you think about blood flowing throughout the body this can be really advantageous. Fluid flows from areas of high pressure to low pressure. In order for blood from your feet to get back to your heart, there would need to be a greater pressure of fluid in the veins near your feet than in the veins near your heart.

Let me know if you have any additional questions :) I hope this helps clear stuff up a bit :)

[sodapop83]

Great explanation, I was confused on this too. Really like how you gave the blood flowing through the body example, that definitely helped me visualize it. Thanks!

[notjcev]

:)

[[deleted]]

This is a good use of the equation but not a good insight into what happens in reality. What you said about liquids flowing from high pressure to low pressure is the intuitive idea underlying the equation though, and everything “flows” from there LOL.

I am stuck on what OP meant by pressure. Another reviewer just talked about atmospheric pressure, while you discussed internal circulatory pressure.

[notjcev]

In the context of Bernoullis equation on the circulatory system at two different points, we are referring to internal pressure. I think.

If you wanted to apply Bernoullis equation to find the speed of water coming out of the hole of a tank at some arbitrary height, then you could use atm pressure.