A strong wind of speed 33 m s–1 blows against a wall. The density of the air is 1.2 kg m–3. The wall has an area of 12 m2 at right angles to the wind velocity. The air has its speed reduced to zero when it hits the wall.

Question

A strong wind of speed 33 m s–1 blows against a wall. The density of the air is 1.2 kg m–3. The wall  has an area of 12 m2  at right angles to the wind velocity. The air has its speed reduced to zero  when it hits the wall.

anonymous · Answer

The pressure at the wall will be (1/2) rho v^2, the "stagnation point pressure." The force will be pressure times area at right angles to the flow. Rho is air density and v is velocity.