A massless spring of spring constant 20 N/m is placed between two carts. Cart 1 has a mass M1 = 5 kg and Cart 2 has a mass M2 = 3 kg. The carts are pushed toward one another until the spring is compressed a distance 1.3 m. The carts are then released and the spring pushes them apart. After the carts are free of the spring, what are their speeds?
conservation of energy
conservation of momentum
The Attempt at a Solution
I have worked on this a bit but can't get the right answer...
I have a conservation of energy equation: .5Kx^2 = .5m1v1^2 + .5m2v2^2
and I also have a conservation of momentum one: Pi = Pf, 0 = m1v1 + m2v2
I tried solving for v1 and plugging it into the first eqn to get a velocity, but I can't seem to get it right...any ideas? Thanks!