3 ms·
I once saw a diagram of a weight suspended from system of string where cutting one of the strings would actually increase the tension on the weight and make it
by raldi 5y ago
I once saw a diagram of a weight suspended from system of string where cutting one of the strings would actually increase the tension on the weight and make it move upwards.
It's impossible to google, though, because the results are all about how to reduce the tension in your life and people's weight going up.
- praptak 5y agoIt is possible to Google: http://web.mit.edu/tsg/DemoPage/B/B17/B17.htm http://web.mit.edu/tsg/DemoPage/B/B17/B17.htm
- rmetzler 5y agoThe German page of the Braess Paradox has a description for this. https://de.wikipedia.org/wiki/Braess-Paradoxon#Mechanisches_Analogon https://de.wikipedia.org/wiki/Braess-Paradoxon#Mechanisches_...
- SilasX 5y agoAh, okay, that helps! So basically, you have a system where two springs are in parallel, thus resulting in effective stiffness being equal to the sum of their stiffnesses (K = k1 + k2). However, the extra linkage makes them act in series, which reduces total stiffness. (1/K = 1/k1 + 1/k2, like parallel resistors). However, I'm blanking on how the analogy to traffic flow works, and on how exactly the blue and red lines are connected to make this work or how stiff they are assumed to be. (I thought they had to be infinitely stiff for this to work but the math on that doesn't work in my quick calculation.) Edit: the German says the three linkages are infinitely stiff (hart) I'm confused because that would make the parallel case infinitely stiff. Edit: Okay I had that wrong, the extra linkages are indeed infinitely stiff. In the parallel case, that doesn't make the system infinitely stiff because each one is in series with a finite stiffness spring. And in the analogy stiffer = shorter travel time, and any road system with a fixed travel time is thus infinitely stiff.
- twic 5y agoThat's in the second figure on the linked wikipedia page - captioned "Comparison of Braess's paradox for road and spring networks".
- deleted 5y ago[deleted]
- thunderbong 5y agoIt's on the same Wikipedia page under Example[0] [0]: https://en.wikipedia.org/wiki/Braess's_paradox#Example https://en.wikipedia.org/wiki/Braess's_paradox#Example