Question

A piece of ice floating in a glass of water melts, but the level of water in the glass does not change.

Give reasons.

Hint: Ice contracts on melting. 

Answer 1

When a floating piece of ice melts into water, it contracts by the volume equal to the volume of ice pieces above the water surface while floating on it. Hence, the level of water does not change when ice floating on it melts.

Answer 2

The fractional part submerged equals the ratio of the density of the material of the block to the density of the liquid.
(Density of floating body / Density of liquid) = fraction submerged.
The Fraction of ice submerged in the water remain the same as the density of ice and water remain the same during melting. As the ice melts some volume of ice decrease and converts into water and volume of water increase by the same amount. So, the level of water remains the same during melting.