(II) A 180km/h wind blowing over the flat roof

aramutselv

aramutselv

Answered question

2022-01-03

(II) A 180km/h wind blowing over the flat roof of a house causes the roof to lift off the house. If the house is 6.2 m×12.4 m in size, estimate the weight of the roof. Assume the roof is not nailed down

Answer & Explanation

kalfswors0m

kalfswors0m

Beginner2022-01-04Added 24 answers

Given:
The speed of the wind, v=180 kmh
=(180×10003600)ms
=50 ms
The area of the house, A=(6.2×12.4)
=76.88 m2
Find the weight of roof.
Here,
Density of air =(0.00129×103 kgm3)=1.29 kgm3
Now,
The pressure of the wind, P=12ρv2
P=12(1.29)(502)=1612.5 Nm2
We know that,
Pressure, P=FA
Here,
F = the force on the roof
A = the area of the roof.
So,
F=P×A=(1612.5×76.88)=123969 N
Therefore,
The weight of the roof, w=123969 N

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