Acar traveling on a straight road at 15.0 meters
per second accelerates uniformly to a speed of
21.0 meters per second in 12.0 seconds. the
total distance traveled by the car in this
12.0-second time interval is
(1) 36.0 m (3) 216 m
(2) 180. m (4) 252 m

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.