In a test experiment on a model aeroplane in a wind tunnel, the flow speeds on the upper and lower surfaces of the wing are `70ms^(-1)` and `83ms^(-1)` respectively. What is the lift on the wing, if its area is `2.5m^(2)`? Take the density of air to be `1.3kgm^(-3)`

Explanation

Let `v_(1),v_(2)` be the speeds on the upper and lower surfaces of the wing of aeroplane, and `P_(1) and P_(2)` be the rpessures on upper and lower surfaces of the wing respectively.
then `v_(1)=70ms^(-1),v_(2)=63ms^(-1),rho=1.3kgm^(-3)` ,brgt from bernoulli's theorem
`(P_(1))/(rho)+gh+(1)/(2)v_(1)^(2)=(P_(2))/(rho)+gh+(1)/(2)v_(2)^(2)`
`therefore(P_(1))/(rho)-(P_(2))/(rho)=(1)/(2)(v_(2)^(2)-v_(1)^(2))` ltbr. or `P_(1)-P_(2)=(1)/(2)rho(v_(2)^(2)-v_(1)^(2))=(1)/(2)xx1.3[(70)^(2)-(63)^(2)]Pa=605.15Pa`.
this difference of pressure provides the lift to the aeroplane. So, lift on the aeroplane
`="pressure difference" xx"area of wings"`
`=605.15xx2.5N=1512.875N`
`=1.51xx10^(3)N`.