I have been given at t=1.00 a position and velocity. And the spring constant and mass. I have found the maximum amplitude. The question is, where was the block at time t=0? And apparently this can be done without solving for the phase constant and making an equation. The question doesn't specify how the block was put into motion. So I don't think you can assume that it started at it's maximum amplitude or was subjected to a force from it's equilibrium. And that's as far as I have got in solving this problem. Is it possible without finding phase constant? Any hints/help?