A box of mass $2\mathrm{.}0$kg is at rest on a tar ramp that is $37$ degrees to the horizontal.

$8\mathrm{.}1$  If the box slides down at constant velocity, what is the coefficient of friction?

$8\mathrm{.}2$  If the box slides toward a section that is now smooth $($but at the same angle$),$ what is the$$acceleration$?$