Question

 A hurricane wind blows across a 7.30 m x 18.5m flat roof at a speed of 150 km/hr 

What is the pressure difference? Express your answer with the appropriate units. 

How much force is exerted on the roof? Express your answer with the appropriate units.

Answer 1

Here you have to assume the density of air as 1.2kg/m3 as nothing is given

Pressure difference P = 1/2×(rho)×v^2

Here p (rho) = density of air = 1.2kg/m3

And v= 150km/h =41.67m/s

So pressure difference P = .5×1.2×41.67×41.67

= 1041.83 N/m2

Now force = pressure × area

F= 1041.83×7.3×18.5

F = 140699.6 N