1. The problem statement, all variables and given/known data Problem: An object of mass m1 elastically collides with an object of mass m2 =(3/2) m1 that is initially at rest. The less massive object has speed v1 and travels at an angle of θ1with its original direction (x-axis) after collision; the more massive object has a speed of v2 = (2/3) v1 and travels at an angle of θ2 after collision. What are the initial speed v0 of the less massive object and the two scattering angles, θ1 and θ2? known values ( symbolically at least) m1 m2 = 1.5 m1 v1f v2f = 2/3 v1f Finding: v0 θ1 θ2 2. Relevant equations Momentum Equations: Pi=Pf KEi=KEf Before: Px: m1*v0 Py: 0 E: 1/2 m1*v0^2 After: Px: m1*v1f*cos(θ1)+3/2 m1 * 2/3 v1f cos(θ2) Py: m1*v1f*sin(θ1)-3/2 m1 * 2/3 v1f sin(θ2) KE: 1/2 m1* v1f^2+1/2 3/2 m1 (2/3v1f)^2 Combined: (1)KE: v0^2=5/3 v1f^2 (2)Px: m1v0 = m1*v1f cos(θ1) + m1*v1f cos(θ2) (3)Py: m1*v1f sin(θ1) = m1*v1f sin(θ2) 3. The attempt at a solution Equation (3)simplifies to sin(θ1)=sin(θ2) (4) θ1=θ2 plugging (3) into (2) (5) v0 = 2*v1f cos(θ1) plugging 5 in to 1 (2 v1f cos(θ1) ) ^2 = 5/3 v1f^2 solving for θ1 you get θ1=arccos( sqrt(15) / 6 ) which means θ2=arccos( sqrt(15)/6) as well From here I am stuck trying to solve for v0. I am also unsure if my value for θ is correct. Thanks for the help.