Question

In a wind tunnel experiment, the pressures on the upper and lower surfaces of the wings are 0.90 x${10}^5$ Pa and 0.91 x 10${}^5$ Pa respectively. If the area of the wing is 40 m${}^2$ the net lifting force on the wing is

• A. 2 x 10${}^4$ N
• B. 4 x 10${}^4$ N
• C. 6 x 10${}^4$ N
• D. 8 x 10${}^4$ N

Answer 1

The correct option is B 4 x 10${}^4$ N

Given data,

Pressure of the upper surface $P_2=0.91\times {10}^{5}Pa$

Pressure of the lower surface $P_1=0.90\times {10}^{5}Pa$

Area$=40m^2$

Force$=?$

Pressure difference which provides the lift

= pressure difference xx Area of the wing

$F=(P_2-P_1)\times A$

$F=(0.91\times {10}^5-0.90\times {10}^5)Pa\times m{s}^{-2}$

$F=0.01\times {10}^{5}Pa\times 40m^2$

$F=4\times {10}^{4}N.$