Question

A block of wood is floating on water at ${20}^o$ with certain volume x above the water level. If the temperature of water is slowly increased, then the volume x

• A. increases.
• B. decreases.
• C. remains same.
• D. first decreases and then increases.

Answer 1

Answer: (B)

decreases.

The up thrust provided by the liquid on the block of wood balances the weight of the wooden block when it floats on water partially submerged.
When the temp of water rises, density decreases.
To balance the weight of the block, more volume has to be submerged in water since density of water decreases.
Hence, the portion of the block of wood above water will decrease with rise in temp.