The world’s largest airplane, the Airbus A380, has a maximum weight of 1,200,000 lbf, wing area of 9100 ft2, wingspan of 262 ft, and CDo 5 0.026. When cruising at maximum weight at 35,000 ft, the four engines each provide 70,000 lbf of thrust. Assuming all lift and drag are due to the wing, estimate the cruise velocity, in mi/h.

The space between two 15-in.-long concentric cylinders is filled with glycerin (viscosity = 8.5 × 10-3 lb·s/ft2). the inner cylinder has a radius of 1 in. and the gap width between cylinders is 0.1 in. determine (a) the torque and (b) the power required to rotate the inner cylinder at 180 rev/min. the outer cylinder is fixed. assume the velocity distribution in the gap to be linear.