A long vertical column is closed at the bottom and open at the top; it is partially filled with a particular liquid and cooled to −5∘C. At this temperature the fluid solidifies below a particular level, remaining liquid above this level. If the temperature is further lowered to −5.2∘C the solid--liquid interface moves upward by 40 cm. The latent heat (per unit mass) is 2 cal/g, and the density of the liquid phase is 1 g/cm3. Find the density of the solid phase. Neglect thermal expansion of all materials.
Hint: Note that the pressure at the original position of the interface remains constant.
Answer: 2.6 g/cm3