1. The problem statement, all variables and given/known data A 2.0 kg ball moving with a speed of 3.0 m/s hits, elastically, an identical stationary ball. If the first ball moves away with angle 30° to the original path, determine: a. the speed of the first ball after the collision. b. the speed and direction of the second ball after the collision. 2. Relevant equations px = p'x (momentum conservation in the x direction) v1x = v1'cosθ + v2'cosθ piy = pfy (momentum conservation in the y direction) 0 = v1'sinθ + v2'sinθ Ki = Kf (conservation of kinetic energy) v1^2 = v1'^2 + v2'^2 3. The attempt at a solution I've attempted solving it in a number of values, but am finding the math challenging and unable to isolate variables. First I attempted to eliminate theta: v1x = v1'cosθ + v2'cosθ v1x - v1'cosθ = v2'cosθ ---square-- v1x^2 - v1'^2cos^2θ = v2'^2cos^2θ 0 = v1'sinθ + v2'sinθ -v1'^2sin^2θ = v2'^2sin^2 add x and y v1x^2 - v1'^2cos^2θ - v1'^2sin^2θ = v2'^2cos^2θ + v2'^2sin^2θ v1x^2 - v1'^2(cos^2θ + sin^2θ) = v2'^2(cos^2θ + sin^2θ) v1^2 - v1'^2 = v2'^2 (v1 - v1')(v1 + v1') = v2'^2 Arranging Energy Conservation, v1^2 = v1'^2 + v2'^2 : v1^2- v1'^2 = v2'^2 (v1 - v1')(v1 + v1') = v2'^2 I feel like I've done something wrong up until this point because everything I get after just doesn't make sense to me. I'm not sure what to equate with what. Help is greatly appreciated!