The Monkey stows out underneath the wing of a jetliner bound to Amsterdam. Curio
ID: 2134154 • Letter: T
Question
The Monkey stows out underneath the wing of a jetliner bound to Amsterdam. Curious as to the mass of the plane, the monkey swings out onto the wing. The wings have a total surface area of 250 m2. The monkey measures the air above the wing to be going by at 300 m/s, compared to 250 m/s below the wing. The ambient air pressure around the plane is 0.5 atm.
a: What is the mass of the plane if this is measured at level flight?
b: What is the mass of another airplane, for which the same results were measured as it was descending at a constant 20 m/s?
Explanation / Answer
P1 + 0.5 rho v1^2 = P2 + 0.5 rho V2^2
P1-P2 =0.5 * 1 * (300^2 -250^2)
P1-P2 = 13750
force F = PA = 13750 * 250 = 3437500
mass of plane = 3437500/10 = 343750 Kgs
b. p1-p2 = (300^2-20^2)/2 = 44800
F = 44800* 250 = 11200000
mass = 1120000 kgs