Question

A 100km/hr wind blows normally against one wall of a house with an area of 50 m/s^2 .Calculate the force exerted on the wall if the air moves parallel to the wall after striking it and has a density of 1.134 kg/m^3.

Answer 1

@Expert , @Vincent-Lyon.Fr

Answer 2

@experimentX

Answer 3

F = 43750 N ?

Answer 4

ys @Vincent-Lyon.Fr
hw did u get it?

Answer 5

\(F=\rho Av^2\)

Answer 6

just put in values?

Answer 7

Yes, with v in m/s, not in km/h and A in m²

Answer 8

there is no need to derive taht formula??

Answer 9

if u can do it @mos1635

Answer 10

do you need it?
it's not simple....

Answer 11

tell anyway

Answer 12

ok
are you familiar with
ΣF=ΔP/Δt
??

Answer 13

ys

Answer 14

newton 2nd law

Answer 15

ok
each molucule of air bounce back from wall (assume elastic collition)
the for 1 molucule ΔP=-2*m*v
so for wall ΔP=2*m*v
at time Δt there will be N molucules that hit wall

those N molucules will be in volume ΔV=A*d
d=v*Δt
and if N'= density in molucules /m^3 then
N=N'*ΔV
N=N'*A*v*Δt

so
F(total)=ΔP(total)/Δt
Ft=N*(2*m*v)/Δt
Ft=N'*A*v*Δt*(2*m*v)/Δt
Ft=N'*A*v*(2*m*v)
Ft=2*N'*m*A*v^2
Ft=2 * ρ * A * v^2
(that factor of 2 is messing thing up :) :) )