Question

A small needle sinks in the water while a piece of wood floats on the water.

Give reasons to explain the above statement.

Answer 1

1. An object floats a liquid when the weight of the object balances the upward push of the liquid or if the object is less dense than the liquid it is immersed in.
2. An object sinks in a liquid when the weight of the object is more than the upward push of water or if the object is denser than the liquid, it is immersed in.
3. For example, a needle sinks in water. On the other hand, when a piece of wood is immersed in water, it will float on the surface with half of its volume in water and half above water.
4. This is because the upward push of water is greater than the weight of wood.
5. Hence, wood floats in water with half its volume immersed in water, and the needle sinks in water.