Question

A 190 km/h wind blowing over the flat roof of a house causes the roof to lift off the house.

If the house is 6.1m x 13.0m in size, estimate the weight of the roof. Assume the roof is not nailed down.

w=___N

Answer 1

Density of wind(air) = 1.2 kg/m^3
Velocity of wind(air) = 190 km/h ==> 52.8 m/s

Using Bernoulli's Equation: P(wind) = (1/2)(density of wind)(velocity of wind)^2
P = (0.5)( 1.29 kg/m^3)(52.8 m/s)^2 = 1798.1568 N/m^2


Pressure = Force/Area
==> Force = (Pressure)(Area) = (1798.1568 N/m^2)(6.1m * 15.0m) = 164531.3472 N
= 1.6*10^5 N.