A 15-kg block is on a ramp which is inclined at 20° above the horizontal. It is connected by a string to a 19-kg mass which hangs over the top edge of the ramp. Assuming that frictional forces may be neglected, what is the downward acceleration of the 19-kg block? 4.0 m/s2, 4.5m/s2, 4.2 m/s2, 3.8m/s2

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.