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alisa.prag7049
Joined: 16 Feb 2010
Posts: 1
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 Posted: Fri Mar 05, 2010 2:17 pm Post subject: Why do we use bernoulli's? |
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| Why can't we use P=F/A and reason that low cross sectional area corresponds to higher pressure? Why do we have to use bernoulli's principle? |
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mcat_premed3832
Joined: 19 Oct 2006
Posts: 427
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| Posted: Fri Mar 05, 2010 9:09 pm Post subject: |
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| mcat_premed3832 wrote: | | We need to apply each equation in their proper context. If you take your finger right now and poke the wall: how much pressure are you applying? |
P = F/A
The force F is the number of newtons you are applying to the wall and the area is the contact area (a square, the side squared; a circle, pi r squared, or whatever).
In general chemistry, the concept of pressure is often discussed for gases in which you are referred to the force of the collisions off of the walls of the container.
Cross sectional area (continuity equation) is not the area of the container. Rather it refers to a specific area within the container (and that specific area may or may not change as you change your position in the container).
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