Practice question · Put in order
Order the reasoning that explains why a roof can be lifted off in a storm (Bernoulli).
- The pressure difference produces a net upward force on the roof
- The still air inside the house keeps full atmospheric pressure
- Along that streamline, high speed means low pressure
- Wind streams fast across the top of the roof
Hints
- Bernoulli’s equation trades speed against pressure along a streamline.
- The dangerous force comes from the difference between inside and outside, not from the wind pushing down.
Show the answer
- Wind streams fast across the top of the roof
- Along that streamline, high speed means low pressure
- The still air inside the house keeps full atmospheric pressure
- The pressure difference produces a net upward force on the roof
Why
Fast exterior flow lowers the outside pressure while indoor air still pushes up at full strength; the imbalance can exceed the roof’s weight. Opening windows on the lee side (equalizing pressure) is real storm advice for exactly this reason.
Practise Fluid Dynamics: Continuity and Bernoulli's Equation
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