Why a thicks walled glass tumbler cracks on pouring boiling water into it?

Answer 1

The boiling water causes the inside surface of the thick glass to expand rapidly. But the outside of the glass expands at a much slower rate, as it takes time for the heat from the inside to reach the outside, and the expansion to equalise. It is this difference in expansion that can cause the glass to break.

Answer 2

Glass is a very poor conductor of heat; the hot water contacts the inside of the tumbler but the outside remains cool; this produces a stress in the tumbler which could crack it since its thermal expansion coefficient may be high; if expansion is low, like Pyrex, it may be OK. Stress is proportional to the glass expansion and temperature gradient and its elastic modulus

Answer 3

The hot water causes the insides of the tumbler to undergo thermal expansion. However, because glass is a poor conductor of heat, the outside of the glass is still at ambient temperature and so has not expanded. The uneven expansion causes the glass to crack.

Answer 4

A thick-walled glass tumbler can crack when boiling water is poured into it due to thermal shock. The sudden and extreme temperature difference between the hot water and the cooler glass can cause the glass to expand rapidly and unevenly, leading to stress fractures and ultimately cracking. It is recommended to use tempered glassware or to preheat the glass with warm water before pouring boiling water to prevent this from happening.