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.

Asheet of steel 1.5 mm thick has nitrogen atmospheres on both sides at 1200oc and is permitted to achieve a steady-state diffusion condition. the diffusion coefficient for nitrogen in steel at this temperature is 6 x 10- 11 m2 /s, and the diffusion flux is found to be 1.2 x 10-7 kg/m2 -s. also, it is known that the concentration of nitrogen in the steel at the high-pressure surface is 4 kg/m3 . how far into the sheet from this high-pressure side will the concentration be 2.0 kg/m3 ? assume a linear concentration profile.