1. The problem statement, all variables and given/known data Two particles of masses m and 8m move toward each other along the x-axis with the same initial speeds of 9.69 m/s. Mass m is traveling to the left and mass 8m to the right. They undergo a head-on elastic collision, and each rebounds along the same line as it approached. Find the final speed of the heavier particle. 2. Relevant equations p = mv ke = 1/2mv2 3. The attempt at a solution 1/2 * m * -9.692 = 46.95mJ 1/2 * 8m * 9.692 = 375.58mJ total ke = 375.58 + 46.95 = 422.53 p = m * -9.69 = 9.69 p = 8m * 9.69 = 77.52 total p = 77.52 - 9.69 = 67.83 so ... p = mv1 + 8mv2 = 67.83 ke = 1/2 * mv12 + 1/2 8mv22 = 422.53 The m's can cancel and I get v1 + 8v2 = 67.83 v1 = 67.83 - 8v2 Then I do not know where to go from here. Do I plug it into the ke equation and solve for v2? Which would give me my answer of the velocity of the heavier particle. Thanks for any help.