In a test experiment on a model aeroplane in wind tunnel, the flow speeds on the upper and lower surfaces of the wings are $70 \mathrm{~ms}^{-1}$ and $65 \mathrm{~ms}^{-1}$ respectively. If the wing area is $2 \mathrm{~m}^2$ the lift of the wing is__________ $\mathrm{N}$.
(Given density of air $=1.2 \mathrm{~kg} \mathrm{~m}^{-3}$ )
JEE MAIN 2024, Diffcult
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$\mathrm{F}=\frac{1}{2} \rho\left(\mathrm{v}_1^2-\mathrm{v}_2^2\right) \mathrm{A}$
$\mathrm{F}=\frac{1}{2} \times 1.2 \times\left(70^2-65^2\right) \times 2$
$=810 \mathrm{~N}$
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