Why does a window shatter when a pebble hits it at high speed?

Question

Why does a window shatter when a pebble hits it at high speed?

Answer 1

the pebble is hard and the window is delicate  glass (i guess)

Answer 2

http://www.md-glass.com/tempered_glass.p...

so if the local pressure due to the pebble ( small area, small time so high rate of change of momentum per unit area = high pressure) gets close to the tensile strength of the outer layers then there's nothing to stop the compressed inner layers bursting out.

  

Answer 3

A lot of factors go into it.

The surface area of a pebble is small, so if it has the same momentum as something larger, it will penetrate more easily because it comes in contact with less of the window. (think of trying to cut something with a knife, which has less surface area on its blade, as opposed to trying to cut something with a baseball bat).

Glass is a crystal, so instead of just going through it, the pebble disrupts its structure, causing it to shatter, or at least crack.