JEE MAIN - Physics (2024 - 29th January Morning Shift - No. 30)
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 _________ $$N$$.
(Given density of air $$=1.2 \mathrm{~kg} \mathrm{~m}^{-3}$$)
Answer
810
Explanation
$$\begin{aligned}
& \mathrm{F}=\frac{1}{2} \rho\left(\mathrm{v}_1^2-\mathrm{v}_2^2\right) \mathrm{A} \\
& \mathrm{F}=\frac{1}{2} \times 1.2 \times\left(70^2-65^2\right) \times 2 \\
& =810 \mathrm{~N}
\end{aligned}$$
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