I don't need help with a homework question so much as a clarification of a concept. I realize that in projectile motion on a horizontal plane, horizontal acceleration is 0. But if an object is launched from the top of an incline (shaped like \), there is both an acceleration along the incline and one normal to the incline, right? The acc normal to the incline should be a = gcos(theta), and the acc along the incline should be a = gsin(theta).
I can see why the acc normal to the plane would become a = -gcos(theta), because the projectile is moving downward. But would the acc along the incline, gsin(theta) become negative as well, since in moving along the range of the incline, it is also moving at a downward angle? Would acceleration along the range be negative as well?
I was just confused because I used a neg acc for "normal" and a positive one for "along the plane," and the answer I received was the negative of the one I should have received. Thanks!