3.5-7 A steel tube (G 5 11.5 3 106 psi) has an outer diameter d2 5 2.0 in. and an inner diameter d1 5 1.5 in. When twisted by a torque T, the tube develops a maximum normal strain of 170 3 1026. What is the magnitude of the applied torque T

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.