Pablo is playing with a hula-hoop (diameter of 112 cm and mass of 858 g). while playing with the hula-hoop, pablo accidently let's it roll down the driveway towards the street. the driveway is 15 m long and has a constant slope of 6 degrees. the hula-hoop starts with a linear speed of 1.30 m/s. find the linear final velocity of the hula-hoop and how long it takes for the hula-hoop to reach the bottom of the driveway.

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.