Experiments were conducted in a wind tunnel with wind velocity 50 km/hr on a flat plate of size 2m long and 1m wide. Take density of air as $1.15kg/m^3$.

Take coefficient of dag as 0.15, and coefficient of lift as 0.75. Determine -

i) Lift Force

ii) Drag Force

iii) Resultant Force

iv)Direction of the resultant force

v) Power exerted by the air on the plate

Solution :

Given :

1. Area of plate, $\quad A=2 \times 1=2 \mathrm{~m}^{2}$

2. Velocity of air, $V =50 \mathrm{~km} / \mathrm{hr} =13.89 \mathrm{~m} / \mathrm{s} $

3. Density of air, $\rho =1.15 \mathrm{~kg} / \mathrm{m}^{3}$

4. Value of $C_{D} =0.15$ and $C_{L}=0.75$

(i) Lift Force $(F_L)$

$$\begin{aligned} F_{L} &=C_{L} \times A \times \rho …