A 10-kg box is shoveled up a 25◦ incline whose coefficient of kinetic friction with the surface of the box is μk = 0.5. What is the magnitude of the acceleration of the box? (note that the acceleration points down the incline and effectively slows down the box, since its velocity is initially up.)
so both gravity and friction are pushing down the slope?
F = m g sin 25 + mu m g cos 25
a =F/m = g sin 25 + .5 g cos 25