1. The problem statement, all variables and given/known data So this is just something i came up with to check if i am understanding everything allright, it all comes down to collisions in regard to the center of mass So two "masses" experience a glancing collision M1: vi - 3m/s (refered to as v1i) ; m - 2Kg (m1) M2 vi - 0 (v2i) ; m - 6Kg (m2) 2. Relevant equations what i did was figure out the speed of the center of mass (Vcm) using: Eq(1) (v1i*m1 +v2i*m2)/(m1+m2) and then since the Vcm is constant before and after the collision (right?) i figured out v1f and v2f because: eq(2) v2f=2vcm-v2i (and same for v1f) this is were i get stuck, using the system: Sys(1) -v1f*m1*sin(theta) + v2f*m2*sin(theta2)=0 m1*v1i=v1f*m1*cosin(theta) + v2f*m2*cosin(theta2) 3. The attempt at a solution so using eq 1 and 2 i get Vcm=3/4 and v1f=-3/2 and v2f=3/2 and i cant solve the system, all the other glancing colision problems i have seen give one of the angles. plus the masses are different so the angle bettwen theta and theta2 isnt 90º, i don't know what to do. I am probably doing something wrong as everything i have seen says i cant solve this kind of problem if i am not given one of the 4 unknown quantities (the two angles and the two final velocities) so probably my mistake is regarding the two final velocities, i dont know.