Asmall metal ball is suspended from the ceiling by a thread of negligible mass. the ball is then set in motion in a horizontal circle so that the thread describes a cone. the acceleration of gravity is 9.8 m/s2, 2.7 m, 6 kg, 31c. what is the speed of the ball when it is in circular motion? answer in units of m/s.

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.