Question

Why does an iron block sink in water but float in mercury?

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 more dense than the liquid, it is immersed in.
3. An iron nail floats on mercury because the density of mercury is greater than the density of iron.
4. But the density of water is less than that of iron so it sinks in water. Because the density of mercury is more than the density of water.
5. Density of iron is less than the density of mercury; hence, an iron nail floats in mercury and the density of iron is more than the density of water; hence, an iron nail sinks in water.

Hence, iron block sink in water but float in mercury.