Question

# A wind with speed $$40$$ m/s blows parallel to the roof of a house. The area of the roof is $$250\ m^2$$. 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 $$(\rho_{air}=1.2 \ kg/m^3)$$

A
2.4×105N, upward
B
2.4×105N, downward
C
4.8×105N, downward
D
4.8×105N, upward

Solution

## The correct option is D $$2.4\times 10^5N$$, upwardApplying Bernoulli's theorem to two points just inside the house and outside the house,$$P + \dfrac{1}{2}\rho v^2 = constant$$Inside the pressure is $$P_{atm}$$The pressure outside is $$P$$v is zero inside.$$\therefore P - P_{atm} = \frac{1}{2}\rho v^2= \frac{1}{2} \times 1.2 \times 40^2=960$$Force is : $$F = (P - P_{atm}) \times Area= 960 \times 250 = 2.4 \times 10^5\:N$$ in upward direction as pressure goes from higher to lower pressure area.Physics

Suggest Corrections

0

Similar questions
View More

People also searched for
View More