1. The problem statement, all variables and given/known data There is no variable for it but we know the angel σ, g, the mass of m1 and m2, m2>m1 and the coordinate system must be considered like that. I know the other method which the coordinate system is parallel to the inclined plane's hypotenuse. 2. Relevant equations F=m*a Newton's Second Law: ƩF=m.a 3. The attempt at a solution Here is a diagram of the what I'm talking about. I found the forces and some equations but I cannot find the acceleration of the system from the datas I found. And I'm not sure if the Normal Force(N) must be considered? Thanks for all the helps.