1. The problem statement, all variables and given/known data A 1.0-kg particle is moving in the +x direction at 4.0m/s when it collides elastically with a 4.0-kg particle moving in the −x direction at 1.0m/s After colliding the 1-kg particle moves oﬀ at 130 counterclockwise from the positive x-axis. Find the final speeds of both particles and the direction of the more massive one. 2. Relevant equations m1*v1=(m1*v3*cos(ø3))+(m2*v4*cos(ø4)) 0=(m2*v4*sinø4)-(m1*v3*sin(ø3)) m1*v1^2 = (m1*(v3)^2) + (m2*(v4)^2) 3. The attempt at a solution (1 kg)(4i m/s) + (4 kg)(-1i m/s) = 0 ==> The total momentum=0 Is there some sort of trick that can be used for 2 dimensional elastic collisions when the masses and speeds swap? Also, since the total momentum is 0, can it be specified as a center-of-mass system, thus being able to use the scattering angle? Thanks in advance for any help!