How do I resolve forces on a slope?

For any question which asks you to consider multiple forces acting on a body, the first thing you should do is draw a clear diagram, with all forces (and in this case angles) labelled.Once this has been done, you can start to resolve in parallel and perpendicular directions relative to the slope. 'Resolve' means to gather all of the components of the forces acting in a particular direction together into one equation. Remember to be careful with +/- signs: the best way is to take the positive direction as the direction in which the object is moving (although it really doesn't matter!).So, if we take an object of mass m ​on a slope which is inclined at A degrees to the horizontal, resolving parrallel to the plane (and by using Newton's Second Law) gives:​mgsin(A) - (Resistive forces) = ma And resolving in the perpendicular plane to the slope:​(Reaction force) = mgcos(A)The main point to remember is to draw a clear diagram - if you do this, hopefully the rest of the question will seem a lot easier!