Net force due to pressure difference?

Question

A wind with speed 45 m/s blows across a roof 20 m long and 12 m wide. The pressure inside the room is 1 atm. What is the net force on this roof due to the pressure difference inside and outside the roof? (The density of air is equal to 1.3 kg/m^3)

Answer 1

Use Bernouli's principle to get the change in air pressure (Hint: It is directly related to velocity^2). See: http://en.wikipedia.org/wiki/Bernoulli%27s_principle#Compressible_fluids

Then multiply the pressure diffence * surface area.