Question

Why does a hot glass chimney often crack when a drop of waterfalls on it?

Answer 1

A hot glass chimney often crack when a drop of water falls on it because the glass of the chimney expands due to constant heating by the flame of the chimney but as a cooler water drop falls on the glass, the outer surface contracts more than the inner side of the glass. This unequal contraction between the two surfaces causes a strain and the glass cracks.