During a winter day, wind at 55 km/h, 5°C, and .1 atmis blowing parallel to a 4-m-high and...

During a winter day, wind at 55 km/h, 5°C, and .1 atmis blowing parallel to a 4-m-high and 10-m-long wall of a house. Approximating the wall surfaces as smooth, determine the friction drag acting on the wall. What would your answer be if the wind velocity has doubled? How realistic is it to treat the flow over side wall surfaces as flow over a flat plat?