When I first read this question I thought it would be simple to solve but apparently it's not, I'm having some difficulty with it. "Two blocks can collide in a one-dimensional collision. The block on the left hass a mass of 0.40 kg and is initially moving to the right at 2.4 m/s toward a second block of mass 0.50 kg that is initially at rest. When the blocks collide, a cocked spring releases 1.2 J of energy into the system. What are the velocities of both blocks following the collision? (For velocities, use + to mean to the right, - to mean to the left.)" At first I tried using a simple conservation of momentum equation m1u1 + m2u2 = m1v1 + m2v2 but then I released this doesn't take into account the 1.2J of energy from the spring. So then I tried solving the question using kinetic energy 0.5mv^2 and I came out with this: 0.5 x 0.4 x 2.4^2 = 1.152J Total energy = initial KE + 1.2J from spring = 2.352J 0.5m1v1^2 + 0.5m2v2^2 = 2.352J 0.2v1^2 + 0.25v2^2 = 2.352J So then I am left with two unknowns and no simple way of solving. I then tried combining both the momentum method and the KE method but that doesn't really work because momentum and energy have different units so cannot be used together. Help!