1. The problem statement, all variables and given/known data A ball of mass m rolls down a 3.0 m ramp inclined at 30° above the horizontal, rolls along a flat, friction less surface, and collides elastically with another ball of mass 2m, initially at rest. The second mass then moves along the surface and collides with a horizontally mounted spring with spring constant k= 200 N/m, compressing it by 0.15 m. What is the value of m? 2. Relevant equations Ek 1 + Eg 1 + Ee 1 = Ek 2 + Eg 1 + Ee 2 For the incline: FN + Fg parallel + Fg perpendicular + Ff = m1a 3. The attempt at a solution I've been working backwards so I started with this: 1/2 m2v2' 2 = 1/2 kx2 I ended up with v2' = √45/2m and I now have no idea how to continue Any help will be appreciated.