[SOLVED] vectors - 1. The problem statement, all variables and given/known data At time t = 0 two forces f1 = (i + j) and f2 = (2i - 2j) start acting on a point body of unit mass lying stationary at the point (1,2) of the x,y plane. Describe the trajectory r(t) of the plane. 2. Relevant equations F = ma a = d2x/dt2 3. The attempt at a solution Total force, F = (i + j) + (2i - 2j) F = (3i - j) I know I need to integrate using the acceleration equation but I'm confused by the x,y plane, I thought it was meant to be in i,j plane? :S Could someone please explain? Thanks!