Ask Questions, Get Answers

Want to ask us a question? Click here
Browse Questions
0 votes

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 $70ms^{-1}$ respectively.What is the lift on the wing if its area is $2.5m^2$?Take the density of air to be $1.3Kgm^{-3}$

$\begin{array}{1 1}(A)\;1\times 10^3N\\(B)\;1.45\times 10^3N\\(C)\;1.51\times 10^3N\\(D)\;2.1\times 10^4N\end{array} $

Can you answer this question?

1 Answer

0 votes
Area of wing $A=2.5m^2$
Density of air $\rho=1.3Kgm^{-3}$
According to Bernoulli's theorem
$P_1+\large\frac{1}{2}$$\rho V_1^2$$=P_2+\large\frac{1}{2}$$\rho V_2^2$
$P_2-P_1=\large\frac{1}{2}$$\rho (V_1^2-V_2^2)$
Where $P_1$ & $P_2$ is the pressure on the upper & lower surface of the ring respectively.
Lift on the wing =$(P_2-P_1)A$
$\Rightarrow \large\frac{1}{2}$$\rho (V_1^2-V_2^2)A$
$\Rightarrow \large\frac{1}{2}$$\times 1.3 (70^2-63^2)\times 2.5$
$\Rightarrow 1.51\times 10^3N$
Therefore lift on the wing of the aeroplane =$1.51\times 10^3N$
Hence (C) is the correct answer.
answered May 9, 2014 by sreemathi.v

Related questions

Ask Question
student study plans
JEE MAIN, CBSE, AIPMT Mobile and Tablet App
The ultimate mobile app to help you crack your examinations
Get the Android App