Need help identifying the force on a roof as a tornado wind passes over it.

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SUMMARY

The discussion focuses on calculating the force exerted on a roof during a tornado, specifically when air flows over a 2200 ft² roof at 136 mph. The relevant equations include Bernoulli's equation and the relationship between pressure and force (P=F/A). A common misconception highlighted is the incorrect assumption that dividing pressure by area yields force, which is incorrect due to unit discrepancies. The expected force magnitude is in the order of x*10^5 N.

PREREQUISITES
  • Understanding of Bernoulli's equation
  • Knowledge of pressure dynamics in fluid mechanics
  • Familiarity with force calculations (P=F/A)
  • Basic concepts of tornado dynamics and wind speed effects
NEXT STEPS
  • Study Bernoulli's equation in detail
  • Research pressure differentials in fluid mechanics
  • Learn about the effects of wind speed on structural integrity
  • Explore real-world applications of force calculations in engineering
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Students in physics or engineering, meteorologists, and professionals involved in structural design and safety assessments during extreme weather events.

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Homework Statement



In a tornado or hurricane, a roof may tear away from the house because of a difference in pressure between the air inside and the air outside. Suppose that air is blowing across the top of a 2200 ft2 roof at 136 mph. What is the magnitude of the force on the roof?

Homework Equations



P1+gρh+.5ρv^2=P2gρh+.5ρv^2
P=F/A

The Attempt at a Solution



I tried to find the pressure above the roof, from Bernoulli's equation, take the difference in pressures above and below, and then divide that by the area...and that was very, very, very much the wrong thing, but I'm not sure why. I know that the answer is supposed to be on the order of x*10^5N.

Thank you!
 
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If you take a pressure and divide by the area, you won't get force. Look at the units.
 

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