A wind with speed 40m /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 [p_("air")=1.2 kg//m^3]

A wind with speed 40m /s blows parallel to the roof of a house. The ar

1.	A wind with speed 40m /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 [p_("air")=1.2 kg//m^3]
Answer» <P>`4.8xx10^5 N`, downwards `4.8xx10^5 N,` upwards `2.4 XX 10^5 N, `upwards `2.4 xx 10^5 N,` downwards Solution :ACCORDING to Bernoulli.s theorem, `p+1/2rho v^2=` constant When pressure INSIDE that house = atmospheric pressure , `p_0`. Let the pressure on the roof be P. `thereforep+1/2 RHO v^2 = p_0+` Clearly, `p_0 gt p` So, effective pressure `p_0-p` willact in the upward direction . `p_0-p=1/2 rho v^2=1/2xx1.2xx(40)^2` Hence, effective force `=1/2xx1.2xx(40)^2xx250=2.4x10^5 N`