Estimating Weight of 6.5m x 15m Flat Roof in Wind

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SUMMARY

The discussion centers on estimating the weight of a flat roof measuring 6.5m x 15m subjected to a wind speed of 190 km/h. Using Bernoulli's equation, the calculated pressure exerted by the wind is 1671.3 Pa. Multiplying this pressure by the roof's area of 97.5 m² yields the force necessary to lift the roof, which directly corresponds to its weight. Therefore, the weight of the roof is equal to the force calculated, confirming that the roof must weigh at least this amount to resist being lifted by the wind.

PREREQUISITES
  • Understanding of Bernoulli's equation
  • Basic knowledge of pressure and force calculations
  • Familiarity with units of measurement (Pa, m²)
  • Concept of equilibrium in physics
NEXT STEPS
  • Study the applications of Bernoulli's equation in fluid dynamics
  • Learn about calculating forces on structures in wind engineering
  • Explore the principles of static equilibrium in physics
  • Investigate methods for securing roofs against wind uplift
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Students in physics or engineering, architects designing roofs, and professionals involved in structural integrity assessments will benefit from this discussion.

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Homework Statement



A 190 km/h wind blowing over the flat roof of a house causes the roof to lift off the house.
If the house is 6.5m x 15m in size, estimate the weight of the roof. Assume the roof is not nailed down.

Homework Equations



Bernoulli's equation : P1 + 1/2pv^2 +pgy = P2 + 1/2pv^2 + pgy

The Attempt at a Solution



i reduced the equation down to 1/2pv^2 to get pressure which numerically was 1671.3 and then i multiplied that by the area which i calculated to be 97.5 m^2, to get the force.

I was clueless on how to approach this problem, but I am even more confused now. please help.
 
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You are done, aren't you? The problem asked for the weight of the roof. In order to lift something, you must apply a force (at least) equal to its weight. If the force you calculated was just enough to lift the roof, then that is the weight of the roof!
 

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