Why do ice cubes crack when you put them in your drink??!
Why do ice cubes crack when you put them in your drink??
just wondering lol, my mate doesnt know so im askin you nice ppl :)
Answers:
the answer is actually thermal shock, the thermal gradient answer is close but the issue is about the rate of change of temperature not the fact that it is getting warmer.
fracture mechanics in solids, ( hard o fracture a liquid dohh ) relies of internal stress this can be like pulling chewing gum which is really elastic and easy to pull apart and eventually it snaps thats called a ductile failure or an window pane shattering under any circumstance thats a brittle fracture.
Brittle fractures are rapid because brittle materials have an internal structure a bit like a crystal where the atoms are all lined up and a crack can find its way between the tiny lined up lines, this crystaline structure allows cracks to propergate, if you go back to the chewing gum example it actually frays at the edge snaps and carrys on stretching because the internal structure is chaotic unless frozen! so cracks cant propergate.
back to the ice, while a trapped air bubble might if the temperature rise got to it expand at a faster rate than the surrounding ice and creat a stress point its an unlikely source of the crack because the bubble will be spherical typically and air is compressible so the ice will typically be able to hold it very nicely ( I wont bore you with the better compressive strength of ice- but it is stronger in compression than tension and bubbles out the ice under compression) the answer is shock, imperfections in the crystaline structure caused by perhaps bubbles or just the patterns of original freezing crate sharp discontinities in the ice structure as soon as on side starts heating at on rate and the other side of a crack at a slightly different one a stress fault occours and the crack which is energy flow propergates down the line of the crystaline interface between the two internal parts of the ice that arwe separated by this. in a case where very very cold ice goes into very ( relative) warm liquid the themal shock might be so great as to give enough thermal energy to blow the ice apart.