1. The problem statement, all variables and given/known data Alpha particle mass - 4amu velocity alpha particle - 3.0x10^5m/s 197Au Nucleus mass - 197amu Head-on elastic collision. Find the final velocity of both the particles 2. Relevant equations Kinetic Energy conserved: 1/2m1v1i = 1/2m1v1f + 1/2m2v2f Momentum Conserved: m1v1i = m1v1f + m2v2f 3. The attempt at a solution For Momentum: 4 x (3 x 10^5) = 4V1f + 197v2f 3 x 10^5 = V1f + 49.25v2f V1f = 3 x 10^5 - 49.25v2f For Kinetic Energy 4 x (3.0 x 10^5)2 = 4V1f2 + 197v2f2 3.6 x 1011 = 4V1f + 197v2f 9 x 1010 = V1f + 49.25v2f Subbing in one for the other 9x 1010 = (300,000 - 49.25v2f)2 + 49.25v2f The v2f and V1f values I get doesn't work out Thanks in advance for your help.