A wooden block floats in water keeping a volume V of it above the surface, at `0^(@)C.` If the temperature of water is slowly raised from `0^(@)C " to " 20^(@)C`, what will be the change in the value of V ?

Explanation

The upthrust of a liquid buoyant force on a floating body depends on the density of the liquid. The part of a floating object above the liquid surface (V, in this case) increases with the increase in density of the liquid.
The density of water at `20^(@)C` is less than that at `0^(@)C.` But, at `4^(@)C`, it is the highest. So, from `0^(@)C " to " 4^(@)C`, V will increase, but after that V will decrease gradually. Eventually, `V_(20) lt V_(0).`