A bureau rests on a rough horizontal surface $($s $=0\mathrm{.}50,$ k $=0\mathrm{.}40).$ A constant

horizontal force, just sufficient to start the bureau in motion, is then applied. $($a$)$ Find the

acceleration of the bureau once it moves. $($b$)$ Repeat the calculations for the bureau on the

incline $(20$o$).$ The force is applied up the incline now.