1. The problem statement, all variables and given/known data Hello everybody, A particle of mass at rest Mo in the laboratory is at rest when it disintegrates into three particles of mass at rest mo. Two of them have velocity and direction as indicated. a. Find the expression of the velocity and angle θ of particle #3. b. Find the ratio Mo/mo. 2. Relevant equations 3. The attempt at a solution In the scheme, we have particle #1 going in the direction <---- with velocity 4c/5, particle #2 with direction perpendicular to #1 going downward with velocity 3c/5, and particle #3 is going upward in the right direction with angle θ. From conservation of momentum: Pi=Pf and P=gamma*m*v I took c=1 P1+P2+P3=0 P1=(4/5)*m/((1-(-4/5)^2)^(1/2)) P2=(3/5)m/((1-(-3/5)^2)^(1/2)) P3=mv/((1-(v)^2)^(1/2)) As, P1+P2+P3=0 ==> P1=-P2-P3 and solve for v ? How to find theta? Thank you!