SOLVED 1. The problem statement, all variables and given/known data A plate of of Mass m contains an ice cube of mass M and side L. Find the shift in centre of mass when th ice melts. (Gravity absent) 3. The attempt at a solution I think that the centre of mass will come down by ML/2(M+m) But my book gives it zero. why? What has gravity to do with centre of mass?? And yes, whats the difference between centre of gravity an centre of mass?