Topic: Fluid Mechanics
A light plane flies at $720~km/hr$ in standard air at an altitude of 1000 m. Determine the stagnation pressure at the leading edge of the wing. Take, $P_{air}=9.0\times10^{4}N/m^{2}$ $\rho=1.1~kg/m^{3}.$
- A. 90 kPa
- B. 119 kPa
- C. 112 kPa
- D. 100 kPa
Answer: C. 112 kPa
Explanation: Velocity $V=720~km/hr = 720 \times \frac{5}{18} = 200~m/s$. Stagnation pressure $P_{s} = P_{0} + \rho\left(\frac{V^{2}}{2}\right) = 9.0\times10^{4} + 1.1 \times \frac{200^{2}}{2} = 90000 + 1.1 \times 20000 = 90000 + 22000 = 112000~Pa = 112~kPa$.