Question 242: Properties of Matter

Question

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 $$=1.2 \mathrm{~kg} \mathrm{~m}^{-3}$$)

Accepted Answer

$$\begin{aligned}
& \mathrm{F}=\frac{1}{2} ho\left(\mathrm{v}_1^2-\mathrm{v}_2^2ight) \mathrm{A} \
& \mathrm{F}=\frac{1}{2} 	imes 1.2 	imes\left(70^2-65^2ight) 	imes 2 \
& =810 \mathrm{~N}
\end{aligned}$$

Properties of Matter

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