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))`

Options

A. `4.8 xx 10^(5) N`, upwards
B. `2.4 xx 10^(5) N`, upwards
C. `2.4 xx 10^(5) N`, downwards
D. `4.8 xx 10^(5) N`, downwards

Explanation

`P_(1) = P_(2) + (1)/(2) rho v^(2)`
`P_(1) - P_(2) = (1)/(2) rho v^(2) = (1)/(2) xx 1.2 xx (40)^(2) = 960 N//m^(2)`
`F = (P_(1) - P_(2)) A = 960 xx 250 = 2.4 10^(5) N`