Question

A block of wood is floating in water at $0 \,{}^\circ C$ . The temperature of water is slowly raised from $0 \,{}^\circ C$ to $10 \,{}^\circ C$ . With the rise in temperature, the volume of block $V$ above water level will

• A. increase
• B. decrease
• C. first increase and then decrease
• D. first decrease and then increase

Answer 1

Answer: (C)

From $0 \,{}^\circ C$ to $4 \,{}^\circ C$ , density of water increases and from $4 \,{}^\circ C$ to $10 \,{}^\circ C$ , density of water decreases.
The volume of block above water will increase with increase in density of water as lesser submerged part is required to create a buoyancy force enough to balance weight of block. Similarly volume of block above water will decrease with decrease in density.