13. If a track athlete runs an 800 m race at a constant speed of 2 m/s, how long will it take her to win the race?
Type A. 6.7 min
your
B. 16 min
answer
C. 26.7 min
D. 400 min

Carbon is allowed to diffuse through a steel plate 15 mm thick. the concentrations of carbon at the two faces are 0.65 and 0.30 kg c/m^3 fe, which are maintained constant. if the preexponential and activation energy are 6.2 x 10-7 m2 /s and 80,000 j/mol, respectively, compute the temperature at which the diffusion flux is 1.43 x 10^-9 kg/m^2 -s.