The eiffel tower has a mass of 7.3 million kilograms and a height of 324 meters. its base is square with a side length of 125 meters. the steel used to make the tower occupies a volume of 930 cubic meters. air has a density of 1.225 kg per cubic meter. suppose the tower was contained in a cylinder. find the mass of the air in the cylinder. is this more or less than the mass of the tower?

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.