Question

1. A jet airplane in level flight has a mass of 8.65 ✕ 10⁴ kg, and the two wings have an estimated total area of 92.0 m².

(a) What is the pressure difference between the lower and upper surfaces of the wings?

(b) If the speed of air under the wings is 226 m/s, what is the speed of the air over the wings? Assume air has a density of 1.29 kg/m³.

2. A long steel I-beam used in bridge construction has a length of 20.0 m. The beam may be exposed to temperatures as low as −21°C in the winter and as high as 38°C

in the summer. What is the difference in length of the beam between these two temperature extremes? (Give the absolute value of the difference. Enter your answer in mm.)

Answer 1

1) Area , A = 92 m^2

m = 8.65 *10^4 Kg

let the pressure difference is P

P * Area = m * g

P * 92 = 8.65 *10^4 * 9.8

P = 9214 Pa

the pressure difference is 9214 Pa

b) let the speed at the top is v

for the pressure difference is P

P = 0.50 * density * (v^2 - 226^2)

9214 = 0.50 * 1.29 * (v^2 - 226^2)

v = 255.6 m/s

the speed of the air over the wings is 255.6 m/s