Calculating Outward Force of a Tornado on a Wall

[kiwikahuna]

Homework Statement

Air within the funnel of a large tornado may have a pressure of only 0.2 atm. Atmospheric pressure is 101300 Pa. What is the approximate outward force F on a 11m X 16 m wall if a tornado suddenly envelopes the house? Answer in units of N.

Homework Equations

P = F/A

The Attempt at a Solution

I converted 0.2 atm to 20260 Pa. The area is 11m X 16 m = 176 m^2.

F = (20260 Pa) (176 m^2)
F = 3.56576 X 10^6 N

The answer is wrong. What did I overlook?

 

[ice109]

is there 0 pressure inside the house?

 

[kiwikahuna]

The problem doesn't say.

 

[Doc Al]

I converted 0.2 atm to 20260 Pa. The area is 11m X 16 m = 176 m^2.

F = (20260 Pa) (176 m^2)
F = 3.56576 X 10^6 N

The answer is wrong. What did I overlook?

For one thing, you only calculated the inward force exerted by the air outside the house. As ice109 says, you forgot that it's the air inside the house that pushes the walls outward. (Find the net force.)

 

[ice109]

The problem doesn't say.

you have to infer it. if this house is inside the atmosphere is there zero pressure inside the house?

 

[ice109]

For one thing, you only calculated the inward force exerted by the air outside the house. As ice109 says, you forgot that it's the air inside the house that pushes the walls outward. (Find the net force.)

cheater...