Question

why does thick glass brake when boiling water is poured while thin glass doesn't?

Answer 1

Vecause in case of hick glass when hot water is poured hen the inner side becomes hot but the outer surface remains cool. So due to unequal temperature it tends t9 break. But in thin glasses when the inner surface gets hot the outer surface also gets hot so it does not break.....

Answer 2

When boiling water is poured into a thick tumbler its inner surface expands. However, due to low thermal conductivity of glass, the expansion of outer surface of the tumbler is quite small. Due to uneven expansion of the outer and inner surfaces, the tumbler breaks.