Hi All, I just have a question regarding potential energies. Say I have a block above a spring, and I define the potential energy of gravity and the spring to be zero at the uncompressed point. I then drop the block, trying to find the maximum compression of the spring using conservation of energy. I also define my coordinate system as the down direction as being positive. If I use conservation of energy equations, do I need to manually put in minus signs? For example in this problem: ΔK + ΔUs + ΔUg = 0 mgh - mgho + .5ky2 = 0 (General equation) Coordinate system down as positive mgh + mgho - .5ky2 = 0 Coordinate system up as positive -mgh - mgho + 5ky2 = 0 Thanks for your help!