# On the dispersion of broken glass **URL:** \ **Category:** Miscellaneous and Personal Stuff I Must Share\ **Created:** [August 11, 2023, 2:42pm UTC](https://boards.straightdope.com/t/on-the-dispersion-of-broken-glass/988409 "2023-08-11T14:42:59Z")\ **Posts on this page:** 11\ **Page:** 1
**Author:** ![CookingWithGas](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/cookingwithgas/32/485_2.png) [@CookingWithGas](https://boards.straightdope.com/u/CookingWithGas)\ **Post date:** [August 11, 2023, 2:42pm UTC](https://boards.straightdope.com/t/on-the-dispersion-of-broken-glass/988409/1 "2023-08-11T14:42:59Z")
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. ---
**Author:** ![Omar\_Little](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/omar_little/32/269_2.png) [@Omar\_Little](https://boards.straightdope.com/u/Omar_Little)\ **Post date:** [August 11, 2023, 2:44pm UTC](https://boards.straightdope.com/t/on-the-dispersion-of-broken-glass/988409/2 "2023-08-11T14:44:16Z")
> [@CookingWithGas](#): > > amazed When this happens, I’m frustrated. Anything but amazed. ---
**Author:** ![CookingWithGas](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/cookingwithgas/32/485_2.png) [@CookingWithGas](https://boards.straightdope.com/u/CookingWithGas)\ **Post date:** [August 11, 2023, 2:47pm UTC](https://boards.straightdope.com/t/on-the-dispersion-of-broken-glass/988409/3 "2023-08-11T14:47:40Z")
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. ---
**Author:** ![burpo\_the\_wonder\_mutt](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/burpo_the_wonder_mutt/32/365_2.png) [@burpo\_the\_wonder\_mutt](https://boards.straightdope.com/u/burpo_the_wonder_mutt)\ **Post date:** [August 11, 2023, 3:00pm UTC](https://boards.straightdope.com/t/on-the-dispersion-of-broken-glass/988409/4 "2023-08-11T15:00:42Z")
It uses the top of your foot as a ramp. ---
**Author:** ![TriPolar](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/tripolar/32/3008_2.png) [@TriPolar](https://boards.straightdope.com/u/TriPolar)\ **Post date:** [August 11, 2023, 3:07pm UTC](https://boards.straightdope.com/t/on-the-dispersion-of-broken-glass/988409/5 "2023-08-11T15:07:53Z")
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. ---
**Author:** ![alovem](https://avatars.discourse-cdn.com/v4/letter/a/b38774/32.png) [@alovem](https://boards.straightdope.com/u/alovem)\ **Post date:** [August 11, 2023, 3:09pm UTC](https://boards.straightdope.com/t/on-the-dispersion-of-broken-glass/988409/6 "2023-08-11T15:09:42Z")
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? ---
**Author:** ![Ponderoid](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/ponderoid/32/19221_2.png) [@Ponderoid](https://boards.straightdope.com/u/Ponderoid)\ **Post date:** [August 11, 2023, 3:12pm UTC](https://boards.straightdope.com/t/on-the-dispersion-of-broken-glass/988409/7 "2023-08-11T15:12:05Z")
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. ---
**Author:** ![Beckdawrek](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/beckdawrek/32/3647_2.png) [@Beckdawrek](https://boards.straightdope.com/u/Beckdawrek)\ **Post date:** [August 11, 2023, 3:36pm UTC](https://boards.straightdope.com/t/on-the-dispersion-of-broken-glass/988409/8 "2023-08-11T15:36:53Z")
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.) ---
**Author:** ![jnglmassiv](https://avatars.discourse-cdn.com/v4/letter/j/f07891/32.png) [@jnglmassiv](https://boards.straightdope.com/u/jnglmassiv)\ **Post date:** [August 11, 2023, 4:19pm UTC](https://boards.straightdope.com/t/on-the-dispersion-of-broken-glass/988409/9 "2023-08-11T16:19:23Z")
> [@Ponderoid](#): > > Such is happening with the glass jar. The tiny pieces will get smacked by bigger pieces and fly further. 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. ---
**Author:** ![InternetLegend](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/internetlegend/32/13154_2.png) [@InternetLegend](https://boards.straightdope.com/u/InternetLegend)\ **Post date:** [August 12, 2023, 5:18am UTC](https://boards.straightdope.com/t/on-the-dispersion-of-broken-glass/988409/10 "2023-08-12T05:18:20Z")
> [@Beckdawrek](#): > > (Cat sauntered away from the scene unscathed. A bit embarrassed, maybe.) If he’s anything like my cats, he wasn’t embarrassed. He _meant_ to do that. ---
**Author:** ![Balance](https://avatars.discourse-cdn.com/v4/letter/b/ccd318/32.png) [@Balance](https://boards.straightdope.com/u/Balance)\ **Post date:** [August 12, 2023, 6:12am UTC](https://boards.straightdope.com/t/on-the-dispersion-of-broken-glass/988409/11 "2023-08-12T06:12:46Z")
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.