Question

a thick glass tumbler often cracks when boiling water is poured into it.why?

Answer 1

When you put the water in the thick glass. thermal conductivity of Glass is very less so the expansion of inner wall is more and Outer wall is less. That's why it break

Answer 2

At the point when a glass is warmed, it's thickness changes and it extends.

At the point when hot water is filled the glass, the internal surface will extend more since more warmth is connected to it when contrasted with the external surface.

Along these lines the glass does not extend in general but rather inward part grows more than the external surface.

This distinction delivers the breaking.

This wonder is known as Thermal Shock.

Glass is more averse to break or break in the event that we warm it up step by step.