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New school level physics problem There is an old physics problem: two holes in the wall of a jar with liquid. The depth of the first hole is x, the second is y. You are to find: the horizontal distance from the jar wall
Not exponential. This time. Guys, there’s always an exponential lurking somewhere. When the rate is proportional to the amount, the amount decays exponentially: a capacitor discharging through a resistor, detergent washi
Pouring-out velocity When solving physics problems at school, I used a standard formula for the velocity of a jet pouring out of a hole, given the pressure inside the liquid and its density. But for a long time I couldn’
Water jets In my childhood library there were many DIY books. One of them, written for young pioneers, described a small setup that demonstrates how jet velocity depends on pressure. At some point I managed to find three
2025 in a nutshell. Kinda... As the owner of this channel and its promoter, I hang out in a lot of Telegram channels. Now there are many posts with promises for the next year. I definitely don’t want to make the gods lau
English joke of the day Vegetarian eats vegetables. Guess what’s for the humanitarian.
Cannabis curve There is a [special page](<https://mathworld.wolfram.com/CannabisCurve.html>) on Wolfram MathWorld dedicated to a very specific equation in polar coordinates. ``` r(θ) = a·[1 + 9/10·cos(8θ)]·[1 + 1/10·cos(
[Chat for discussions](<https://t.me/phys_math_dev_chat>) Feel free to discuss things there [invitation link](<https://t.me/+Au96VWrWbB5iYmIy>)
Walrus operator To finalize previous post. ```python n = 0 while (s := input()).lower() != "конец": n += 1 print(n) ``` I think, it's the most elegant approach. But it uses "walrus operator" which appeared only in python
De Morgan's rule One of the subscribers brought me a problem. Roughly, it sounds like this: “Read standard input and count strings. Stop counting when the user enters конец or КОНЕЦ.” The question was how to write the lo
Algorithm Flood In comments you can bring interesting programming tasks and discuss it
Qbasic and polar coordinates I think it's quite a controversial take. Progress gives us far more powerful computers, instruments nobody could imagine 5 years ago. And still qbasic feels like the best way to start writing
Word of the day: spendthrift Spend means “to give away”, thrift — “to keep”. If you know these words, spendthrift may sound like “keep your money while you can”. And that would be totally wrong. Spendthrift means to spen
Sine cosine machine I’m a physicist, and for me sine and cosine are first and foremost laws of motion: the horizontal and vertical shadows of a pin on the edge of a rotating disc, cast on a wall. Some time ago I decided
Sunflowers. MapReduce. P.S. While writing this post, I realized this algorithm can be improved. There’s some unnecessary work: first I build a (x, y) → h dictionary, and then I rebuild it into h → [(xi, yi), …]. We can g
MapReduce in The Farmer Was Replaced Code discussion. Part II. In the [previous post](<https://t.me/phys_math_dev/86>) we discussed [the code](<https://github.com/tarstars/tfwr/blob/main/sunflowers_ach.py>) which uses ma
Competitive programming guides. When somebody asks about best guides for competitive programming, my first reaction is: * [A. Shen: "Programming: theorems and problems"](<https://sch57.ru/files/pub/prog/Programming_theor
Word of the day I’m in ɔ of this world. Three letters → one ɔ.