A block of wood is floating on water at `0^(@)C` with a certain volume `V` above water level. The temperature of water is slowly raised to `20^(@)C` . How does the volume `V` change with the rise of temperature ?

Explanation

If `rho` is the density of water in which the block is floating with volume `upsilon` in water, then weight of block, `W= upsilon rho g`. We know that with the rise in temperature water contracts from `0^(@)C` to `4^(@)C` and then expands form `4^(@)C` to onwards (due to anomolous expansion of water). Thus the density of water will increase from `0^(@)C` to `4^(@)C` and then will decrease. Therefore, to provide proper upthrust (=weight of wood) for floating the volume `upsilon` will decrease from `0^(@)C` to `4^(@)C` and then will increase from `0^(@)C` to `4^(@)C` and then will decrease with further increase in temperature.