The forces acting on an object on a slope are the normal contact force N which is perpendicular the plane of the slope, the weight W of the object which acts downwards towards the centre of the Earth, and friction F which opposes the motion of the object down the slope so acts up the slope.
The weight mg can be resolved into two components parallel and perpendicular to the slope.
N = mg cos αIf friction is negligible, mg sin α = m aa = g sin α
The weight mg can be resolved into two components parallel and perpendicular to the slope.
N = mg cos αIf friction is negligible, mg sin α = m aa = g sin α