A frustrating question regarding pressure, fluid and force

AI Thread Summary
The discussion revolves around a physics homework problem involving the conditions under which an iron plate will rise due to airflow above it. The key parameters provided include atmospheric pressure, air density, and gravitational acceleration, while the thickness of the plate is specified. The solution involves applying Bernoulli's equation to relate the pressure difference created by the airflow to the weight of the plate. The final calculated speed of airflow required for the plate to rise is 15.4 m/s. The conversation emphasizes the importance of understanding the relationship between pressure, fluid dynamics, and force without needing the area of the plate for this specific calculation.
erinec
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Homework Statement



In an experiment a student arranges for air to blow across top of an iron plate that has a large area and a thickness, d, of 2.0 mm. The air underneath the plate is at rest.

What is the speed of air flow above which the student would observe the plate to rise? (Ignore the small buoyancy force of the air acting on the heavy plate. i.e. ignore pairgd.)

Patmosphere = 101300 Pa
Density of air = 1.29 kg/m3
g = 9.81 m/s2

Homework Equations


Bernoulli's
P + 1/2 pv2 + pgh = constant


The Attempt at a Solution


The answer is apparently v = 15.4 m/s.

But I do not know how to even start this question as only little data is given.

Your help will be very appreciated. Or any suggestions/ideas/hint would help a lot as well.
 
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You have to assume the density of iron plate.
 
Thanks for your reply.

But even if I know the density of the iron plate, I am not given the area of the plate, so it won't be much of a use, no?
 
To find the pressure area is not needed. Density is enough.

p(iron)dg = 1/2*p(air)*v^2. Try this.
 
Yes you are right.
Thank you so much.
 

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