where can i find info on why glasses cracks when you pour water in it?

Answer 1

Right here

Glass expands when it gets hot and contracts when it gets cold.

so when you pour hot water into a cold glass, the inside of the glass starts to expand much faster then the outside of the glass can handle - and it cracks. The thicker the glass, the more likely it is to crack

vice cersa for putting cold water into a hot glass

Answer 2

This is known as thermal shock fracture. When objects heat up, they expand, when they cool down, they shrink (water ice is the exception to this). When something hot has cool water poured on it, the outer portions cool faster than the inner portions causing internall stresses which eventually cause the object to fracture. This can occure very violently causing the object to appear to explode in some cases.

Answer 3

It works both ways, if you pour really cold water in a really hot glass pan, it will shatter (sometimes explosively).