Fluid Mechanics Viscosity Question 280
Question: A wind with speed 40 m/s blows parallel to the roof of a house. The area of the roof is$ 250m^{2} $ . Assuming that the pressure inside the house is atmospheric pressure, the force exerted by the wind on the roof and the direction of the force will be($ {\rho_{air}}=1.2kg/m^{3} $ )
Options:
A) $ 4.8\times 10^{5}N,upwards $
B) $ 2.4\times 10^{5}N,upwards $
C) $ 2.4\times 10^{5}N,downwards $
D) $ 4.8\times 10^{5}N,downwards $
Show Answer
Answer:
Correct Answer: B
Solution:
[b] According to Bernoulli’s theorem, $ P+{2}^{1}\rho v^{2}=P{0}+0 $ $ So,,,,\Delta P=\frac{1}{2}\rho v^{2} $ $ F=\Delta PA=\frac{1}{2}\rho v^{2}A $ $ =\frac{1}{2}\times 1.2\times 40\times 40\times 250=2.4\times 10^{5}N $ (upwards)
BETA
