Why is broken glass so sharp?

Question

I've always wondered why people bleed so badly when they get cut by broken glass. Does it have to do with the composition of glass (i.e. what substances glass is made of)?

Answer 1

Glass-like things like flint, glass and the like are hard and inflexible so fracturing results in an edge only a fraction of a micron thick, on the scale of a few molecules, as opposed to harder materials like metals which are malleable and flex so that it is virtually impossible to hone an edge that thin. Basically, the thinner the edge, the "sharper".

Answer 2

Think of it statistically. If you have a sheet of glass for simplicity, say a window, and you break it, each one of the comlpete fractures goes from one side to the other. The dullest possible crack would be at exactly a right angle though the glass, which is only ONE of an infinite number of possibilities. In other words, there are an infinite more number of ways that the glass can break "sharply" as opposed to breaking "dully".