So this sounds homework question but I promise its not. At least its not mine. I saw it on a website because someone made it funny because of what they answered (drew an elephant if you know the one I'm talking about) Anyway, so the problem was a block of mass m = 5 kg falls starting at rest at h = 5 m down a curved frictionless ramp into a spring with spring constant k = 100 N/m. Find the distance it compresses x and find the height the block comes back up to. I understand using gravitational potential energy is equal to spring/elastic potential energy at the max compression to find x, but what I don't quite get is finding the max height the block comes back up to. I'm finding online that its the same as the starting height because all the potential energy in the spring is pushed back in to the block and since the ramp is frictionless. But wouldn't the spring still oscillate hinting that it has energy? If it has energy, wouldn't this energy had to have been taken from the kinetic energy of the block? Otherwise how does the spring get the energy to oscillate and still push the block back up to initial height?