A cube of ice of edge 4 cm is placed in an empty cylindrical glass of inner diameter 6 cm.
Question:

A cube of ice of edge $4 \mathrm{~cm}$ is placed in an empty cylindrical glass of inner diameter $6 \mathrm{~cm}$. Assume that the ice melts uniformly from each side so that it always retains its cubical shape. Remembering that ice is lighter than water, find the length of the edge of the ice cube at the instant it just contact with the bottom of the glass.

Solution: