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A jet airplane flying at constant speed and in level flight, has a mass of m=8.66*104 kg and a combined wing surface area of A=90.0 m3. Assume that the density of the air at the altitude of the jet is pair=1.29 kg/m3 and that g=9.8 m/s2. You can ignore the difference in gravitational potential energy between the upper and lower surfaces of the wings.
Bernoulli’s Equation: P1 + ½pv12 + pgy1 = P2 + ½pv22 + pgy2
A.) What is the weight (w) of the jet airplane?
B.) For the airplane to maintain level flight, the lift must be equal in magnitude and opposite in direction to the force of gravity (that is, the weight). In a free-body diagram, we would have L = w. What is the magnitude of the lift (L)?
C.) Assume that lift is the difference in force between the lower and upper wings and that pressure is force per unit area (in this case, the area of the wings), what is the difference in pressure (change in P) between the lower and upper wing surfaces (pay attention to the sign)? Note: On the lower wing, the force pushes up while on the upper wing the force pushes down—If the plane is to fly, the force on the lower wing must be greater than the force on the upper wing.
D.) Assume the speed under the wing is 225 m/s, what is the speed over the top of the wing (Use Bernoulli’s equation and ignore the difference in gravity between the upper and lower wings, that is, p*g*r*change in y=0)?
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