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from the things-that-go-clunk-in-the-shower dept.
Why is an empty shampoo bottle so easy to knock over?:
It becomes annoyingly easy to knock over a shampoo bottle when it's nearly empty. This is an easily observed and curiosity-provoking phenomenon that, according to Lehigh University physics professor Jerome Licini, yields insights into center-of-mass and impacts.
"The physics of that is pretty interesting and easy to understand," says Licini who, along with first-year physics major Allen Zijun Yuan, wrote a paper on the phenomenon that was recently published in The Physics Teacher. In the paper, they find the center-of-mass of a shampoo bottle, discuss its stability on a tilted surface, and demonstrate its sensitivity to impacts using a simple experiment involving a tennis ball and a protractor.
They write: "An object placed on a tilted surface and released will tip over if the horizontal position of the center of mass lies outside the geometric outline of the base of the object. This means that an object with a low center of mass will be stable for larger incline angles. Students are often surprised to see that the altitude of the center of mass of a shampoo bottle is a nonlinear function of the fraction occupied by the contents. This can, however, be seen in a straightforward manner by recognizing that for a plastic bottle, the mass of the liquid contents is usually far greater than the mass of the bottle. When the bottle is either completely full or completely empty, the center of mass must be approximately at the geometric center of the bottle, but the center of mass gets significantly lower in altitude for small liquid levels in between those two extremes."
Yuan developed a demonstration to show the effect of impact and, it turns out, even more extreme than just looking at angle.
Reference:
Why is an empty shampoo bottle so easy to knock over? The Physics Teacher (DOI: 10.1119/1.5145426[$]) (free access link)
(Score: 2) by Gaaark on Thursday March 12 2020, @03:47PM (8 children)
Nothing to see here but idiot students who just figured out simple physics.
Caps are heavy, bottoms usually small: bottle is top heavy and will fall over. Oooh, gimme a peese prize!
Shit: for a LOT of bottles on the shelf FULL, they are easy to knock over BECAUSE of the small bottoms. Duh.
--- Please remind me if I haven't been civil to you: I'm channeling MDC. ---Gaaark 2.0 ---
(Score: 0) by Anonymous Coward on Thursday March 12 2020, @03:52PM
No peese in the shower.
(Score: 1, Touché) by Anonymous Coward on Thursday March 12 2020, @05:32PM (3 children)
But of course, you were born with infused universal knowledge of everything...
You're the perfect example of the maladapted, socially inept, autistic assholes that infect the internet like a plague.
(Score: 0, Insightful) by Anonymous Coward on Thursday March 12 2020, @05:56PM (1 child)
Or, maybe like me, he built towers out of blocks as a kid. This develops a somewhat intuitive sense of where the center of gravity is located (due to offset blocks) and the consequences thereof. No snark necessary, just good play.
(Score: 0) by Anonymous Coward on Thursday March 12 2020, @10:32PM
So how did you get your Weebles to fall over? Mine never did. That is at least a little bit relevant here beyond your wooden block model.
(Score: 2) by Gaaark on Friday March 13 2020, @02:50AM
And you seem to just be stupid! You didn't have this figured out as a kid?
--- Please remind me if I haven't been civil to you: I'm channeling MDC. ---Gaaark 2.0 ---
(Score: 2) by DannyB on Thursday March 12 2020, @08:07PM (2 children)
I never like to be disagreeable, but I must disagree.
One major bit of scientific knowledge comes from this.
If you play your cards right, you might be able to get a grant to study something like this.
Maybe I'm in the wrong profession.
To transfer files: right-click on file, pick Copy. Unplug mouse, plug mouse into other computer. Right-click, paste.
(Score: 0) by Anonymous Coward on Thursday March 12 2020, @09:39PM
Yeah maybe you could be a stock market pundit or "a business guy" and see all your predictions come false every other day and still get paid for it.
(Score: 0) by Anonymous Coward on Thursday March 12 2020, @10:29PM
As far as I can tell, this was not supported by any grants or outside funding. This doesn't surprise me given that it is a small paper in The Physics Teacher.
You prefer the lecture-textbook-only model of teaching? I would wager that the first-year undergraduate student learned a great deal on this project, and to come out with a paper co-authorship too is a nice bonus.