Question

A hollow glass sphere which floats with its entire volume submerged in water at 40°C, sinks when water is heated above 40°C. Give reasons.

Answer 1

Answer:

It so because of the unique property of water, almost every liquid contracts when cooled /frozen but in the case of water, it contracts till 4 degree celsius and expands if  it's temperature is reduced further ,at this temperature (4 degree celsius) point it has the highest density and so the sphere floats. Now, if we decrease or increase it's temperature it will expand, lowering it's density, hence the sphere sinks.

Answer 2

Answer:

This is because at 4 degrees celcius, water is at its peak density. This high density is due to the fact that water at this temperature gets more contracted than usual and will have a low volume with a higher density.