Can anyone help me with this question. I'm not really sure where to start. A wind with speed 45m/s blows across a roof 20m long and 12m wide. The pressure inside the room is 1x10^5 Pa. Neglecting the small difference in thickness of the roof, what is the net force on this roof due to the pressure difference inside and outside? The density of air is equal to 1.3kg/m^3. Please help.