Which of these is an example of the conversion of kinetic energy into gravitational potential energy?a. a car engine moving the car forwardb. a bicyclist coasting down a long hillc. a thrown ball falling toward the ground after passing through the top part of its motionSelected:d. a roller coaster car moving toward the top of a rise in the tracks

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.