1. The problem statement, all variables and given/known data In http://session.masteringphysics.com/problemAsset/1007030/9/yf_Figure_5_72.jpg I have to find the number of revolutions per minute at which the lower cord goes slack. 3. The attempt at a solution I just need to be sure: What they are asking me to find is the number of revolutions, so the lower cord is still tight, but it's the limit - so if the revolutions is a teeny weeny bit smaller, it goes slack? If I have understood it correctly, is this the number of revolutions at which the block is only affected by the upper cord, and then the number of revolutions has be to bigger than that number? I hope you get me. Thanks in advance.