# Bernoulli's

Discussion in 'MCAT Study Question Q&A' started by bajoneswadup, 04.16.12.

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1. ### bajoneswadup

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Ok I know there's thousands of threads like this, but my physics
prof skipped fluids, so will somebody tell me that I'm correct.

Ok in a closed system only relate area w/ the velocity b/c flow rate
is constant Q=av. Then I relate the velocity to the pressure w/ Bernoullis's. This is the typical thought process right?

In an open system if P increased V can increase too, but in a closed system they're inversly related. Do I need to know anything else about Bernoulli's, like the v is squared? Or am I straight?

Also, how do I know when to apply Poiseuille's law vs q=av?

Last edited: 04.16.12
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3. ### SaintJude

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Bernoulli, pressure straight up related to velocity bro, super impertanto --check it out

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Hahaha

5. ### syoungMS-3 5+ Year Member

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don't pressure me, bro!

6. ### SaintJude

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Ok, now in all seriousness, the most important relationship from Bernoulli is that as velocity increase, pressure decreases. Also I pm'd you a good source for more info.

7. ### milski1K member 5+ Year Member

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I think you're ok.

Poiseuille's law and q=av are not contradictory. The former gives you the pressure difference along a pipe for a non-ideal, viscous fluid. q=av just relates the velocity and the flow at a specific cross-section of the pipe. It will be correct for any non-compressible fluid.

8. ### Tatiana3325BannedBanned

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Bernoulli's equation:
Where 1. Points one and two lie on a streamline, 2. The fluid has constant density, 3. The flow is steady, and 4. There is no friction

Fluid= gas or liquid

Increase in fluid speed results in decrease of internal pressure. And vice versa.

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