1. The problem statement, all variables and given/known data http://i261.photobucket.com/albums/ii53/dimios-4-/free_body_4-1.jpg 2 masses m1,m2 are combined with a baton(stick) to a system.first the system is unmovabble.then after the strike of Mo with the m2 the velocity of Vo=Vf=1. BUT the Vf,V2 are vertical.the Uo is parallel to x axis.the Vf is parallel to y axis who can i find the Vc(velocity of the center mass)m1,m2 ? I am really sorry i make a mistake.Vf is the velocity of mass Mo after the strike 2. Relevant equations i am confused.i have to use the p conservation (Pbef=Paft) in the 3 masses ir in the 2 masses?The kinetic energy cons.also in 3 masses?Who does the stick(with no mass)affest to these laws? 3. The attempt at a solution because of concetration of p=mv in the L-system i have Pbef.=Paft <=> vectors .. Pox=Puf+P1+P'o x ,y-->x,y axis Puf=P2y Kaft-Kbef=1/2(m1+m2)Vc^2 + MoV'o is that correct ?