1. The problem statement, all variables and given/known data A particle leaves the origin with a velocity of 7.2 m/s in the positive y direction and moves in the xy plane with a constant acceleration of (3.0i - 2.0j) m/s2. At the instant the particle moves back across the x axis (y=0), what is the value of its x coordinate? 2. Relevant equations vxf=vxi+axt xf=xi+.5(vxf+vxi)t xf=xi+vxit+.5axt2 v2xf=v2xi+2ax(xf-xi) 3. The attempt at a solution Are my x and y initial (0,0) because it says origin? Do I have to used to substitution as well?