Re: OT: central limit theorem

On 2024-04-26 15:30, Joe Gwinn wrote:

On Fri, 26 Apr 2024 14:46:52 -0400, bitrex <user@example.net> wrote:
 

I have one of these inexpensive Ikea bookshelves for storing some of my
electronics books:
>
<https://www.ikea.com/us/en/p/laiva-bookcase-black-brown-40178591/>
>
I noticed the center shelf was starting to sag a few degrees. :( The
assembly manual specifies a weight limit of 33 lbs evenly distributed
which seemed like an oddly specific number. So I weighed the books on
the shelves, which aren't particularly well organized other than to
fully fill the available space widthwise on each shelf.
>
A random assortment of hardbacks and paperbacks, some are tall and
skinny, some are short and fat. And each shelf was clocking in at 33 lbs
+/- 2 lbs.

 Ikea shelves are made of veneered particle board, and can creep under
steady load.  Is it possible to flip the shelf planks upside down, so
they start to creep back towards straight?
 

So I guess a heuristic for filling these shelves is just fill 'em up
then remove the heaviest book, and de-rate the center shelf by maybe 5-
10 lbs because it's unsupported by a backing.

 If the shelf plank material is creeping, this won't work.
 Joe Gwinn
 

The OP might want to upgrade to Ivar shelves. I’ve got probably a dozen sections, 7 feet tall, and Ikea still sells them, I think.
Inexpensive, solid wood, good looking, super strong, and last forever.
Otherwise they stink.
Cheers
Phil Hobbs
--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC / Hobbs ElectroOptics
Optics, Electro-optics, Photonics, Analog Electronics
Briarcliff Manor NY 10510
http://electrooptical.net
http://hobbs-eo.com