I am always amazed that if a glass or jar tips off the counter and breaks on the floor, I am still finding bits of glass 20 feet away days later.
When this happens, I’m frustrated. Anything but amazed.
I can’t figure out where the energy comes from that propels an object laterally for 20 feet after it has fallen vertically for 3 feet.
It uses the top of your foot as a ramp.
It is shattering, and if starts near the part that hits the floor first then the weight of the rest of the jar coming down could propel little bits a long way.
It stands to reason that some of the smaller shards could be spread after sticking to the bottom of your shoes, slippers, etc. You’d notice them straight away if you walked around barefoot in the area of impact, but who does that?
Try holding a basketball in the air with a tennis ball positioned on top. Hold them in place and then drop them together. The tennis ball will fly way higher than the position it was dropped from. It stole momentum from the basketball, which hardly misses it, given its much greater mass. Such is happening with the glass jar. The tiny pieces will get smacked by bigger pieces and fly further.
I had a glass shade (old glass, not sure if that makes any difference) on a hanging light.
My cat jumped at a moth. Cat, gobe and stuff on a tabletop flew in a tornado of objects to the floor via the the table edge.
I found glass for months.
One piece was on top the refrigerator.
(Cat sauntered away from the scene unscathed. A bit embarrassed, maybe.)
That’s true and also many glass items have enormous internal pressures in their molecular structure. They’re barely holding themselves together before a tiny crack or chip propagates through and the bits fly apart like springs from grandpa’s watch.
If he’s anything like my cats, he wasn’t embarrassed. He meant to do that.
Following up on what TriPolar and Ponderoid said: imagine that the piece of glass is the row of steel spheres in a Newton’s Cradle. Swing a sphere at one end into the stationary middle ones, and the other end goes flying. Since the “other end” in this case is a low-mass shard relative to the total mass of the glass object, the force applied accelerates it more.
The internal tension jnglmassiv mentions is another factor, though probably not a major one in a drinking glass. I’ll bring in another special case, though: internal or external pressure on the glass can impart still more force to the shattered pieces. One of the scariest incidents I recall from working in my family TV shop was when a large CRT (the bare tube from a very old 25" TV) fell off a bench and landed face-down on concrete. The instant the impact cracked the glass, it imploded due to the vacuum inside, sucking shards into the center and flinging them out again. Bits of glass were embedded in wooden cabinet fronts all over the room.