A student marks his starting point on a grassy field. He then makes three moves: 20 m east, 40 m north, and 80 m west. Where is his final position relative to his starting point? a 60 m east and 40 m north b 40 m west and 60 m north c 60 m east and 40 m south d 60 m west and 40 m north e 40 m east and 60 m south

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.