Question

A block of wood is floating on water at $0^{\circ }C$, with a certain volume V above water level. The temperature of water is slowly raised from $0^{\circ }C$. How will the volume V change with the rise of temperature?

• A. V will be unchanged
• B. V will decrease from $0^{\circ }C$
• C. V will decrease till $4^{\circ }C$ and then increase
• D. V will increase till $4^{\circ }C$ and then decrease

Answer 1

The correct option is D V will increase till $4^{\circ }C$ and then decrease

Let the total volume of the wooden block be $V_o$

Then the volume of water displaced by block at any given temperature $=V_o-V$

The block remains in equilibrium at all temperatures. Thus, weigh of block $=mg=(V_o-V){\rho }_{w}g$

$V=V_o-\frac{mg}{{\rho }_{w}g}$

here, ${\rho }_w$ is density of water.

We know that density of water is maximum at $4^{o}C$.

Thus the value of $V$ is maximum at $4^{o}C$