A bomb with 8 x 10 with the power of 4 J of potential energy explodes. Assume 20 percent of its potential energy is converted to the kinetic energy of the metal pieces flying outward (shrapnel). The total kinetic energy is 1.6 x 10 to the power of 4 J. Assume the average mass of the shrapnel is 0.4 kg and that there are 200 pieces. What is the average speed of one piece?

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.