Euler’s Disk
An evening pause: Something for all those new home schoolers, and their parents, to puzzle over and use to learn something worthwhile and real.
Note also how the concave mirror eventually forces the disk into the center of the mirror.
Hat tip Phill Oltmann.
My July fund-raising campaign for 2021 has now ended. Thank you all for your donations and subscriptions. While this year’s campaign was not as spectacular as last year’s, it was the second best July campaign since I began this website.
And if you have not yet donated or subscribed, and you think what I write here is worth your support, you can still do so. I depend on this support to remain independent and free to write what I believe, without any pressure from others. Nor do I accept advertisements, or use oppressive social media companies like Google, Twitter, and Facebook. I depend wholly on the direct support of my readers.
If you choose to help, you can contribute via Patreon or PayPal. To use Patreon, go to my website there and pick one of five monthly subscription amounts, or by making a one-time donation. For PayPal click one of the following buttons:
If Patreon or Paypal don't work for you, you can support Behind The Black directly by sending your donation by check, payable to Robert Zimmerman, to
Behind The Black
c/o Robert Zimmerman
P.O.Box 1262
Cortaro, AZ 85652
Highly suggest any of the physics lectures from Walter Lewin for home-schooling purposes. (High school level.)
–Get yourself a free test-copy (full functionality for 1 month) of Internet Download Manager (or similar downloading Program), download them all off yt, and burn them to DVD. (This by-passes all inserted commercials, and you have a physical copy.)
[If you want ‘mental hygiene films’ from the 1950/1960’s, go to the Archive(dot)org.
Professor Walter Lewin
“I am Still Alive Because of D-Day”
June 6, 2018
https://youtu.be/p5bsw8GNqCM
3:11
a sample….
MIT Physics 8.01x
“Lecture 6 – Newton’s Laws”
Walter Lewin
https://youtu.be/oduZsA0Tk58
49:15
“Watch all my 94 MIT course lectures. Start with 8.01, then 8.02, then 8.03. Do all the homework and take all my exams. Homework and exams are posted below the video thumbnails. I guarantee you, that you will then not fail the Physics portion of any exam.”
Now I wonder if this has a thermodynamic counterpart with “anti-freezing:”
“When vibrations increase on cooling: Anti-freezing observed”
From Aug 4 2021 phys.org at Helmholtz Association… nickel oxide.
The term anti-freezing made me think back to Egon Bach’s ideas of work and “anti-work” when it came to “geometeors” as Olkhovatov thought Tunguska was..