Scanning fidget spinner

Hi,

Its been about two weeks since I watched this video about rolling shutter and also this video by Matt Parker whom I mentioned last time. Matt was showing the effect on fidget spinner, the new gadget that you simply spin and there is nothing really special about it (except that it spins).FidgetSpinner


Rolling shutter is the effect made by any “picture taking device” (as far as I know). So, for example camera or scanner (in my case). When cameras take pictures, they do so by scanning from top to bottom and saving up line by line of pixels. Similarly, how scanners do it except much faster so that you do not notice it. Scanner on the other hand is slow enough that when something is moving the pictures won’t make any sense. If I would move an object with the scanner, at the same speed it would smooshed across the whole picture because it does not see everything at once, only a thin line.

FidgetSpinner2

Really interesting stuff starts to happen when you spin something so that it goes back and forth (around and around). I did exactly that and it produced for example image above or the ones to the side.

It is interesting how the twisted shapes change with the speed that the fidget is rotating. The fifth and sixth picture are part of the same thing, fidget spinner spinning and being moved by me at the same time. The first one on the collage is spinning really fast, the second one not so much the third one is changing directions and the fourth one is really slow which makes for quite “solid” fidget spinner.

I recommend to try this at home, great and easy “experiment” (of course unless you do not have fidget spinner, then I do not recommend buying (life at stake)).

Dragallur

Swap the numbers

Hi,
I am reading a book from Matt Parker now. It is called “Things to make and do in the fourth dimension” and the ~200 pages that I read are quiet amazing. The author is also YouTuber and it seems that he mostly does “Standupmaths” which is cool channel. I got inspired a bit and created this game that I started to call “Swap the numbers”.


I was thinking about battery on my phone and how it is going down and that it would be interesting, if the first and second number swapped with the first after subtraction of 1,2 or 3 or more percent at a time. I wrote down bunch sequences, beginning with 100 and going down by one digit numbers.

It is not finished since I want to find a way to predict how these sequences form and I have not figured it out yet. I will give an example and then show why this game is so peculiar.

Let’s say that we subtract the number four, that is the one that I started with:

100 (subtract four) 96 (swap both digits) 69 (subtract four) 65 (and so on…) 56 52 25 21 12 8 80 76 67 63 36 32 23 19 91 87 78 74 47 43 34 30 3 -1 10 6 60 56 65 61 16 12 21 17 71 67 76 72 27 23 32 28 82 78 87 83 38 34 43 39 93 89 98 94 49 45 54 50 5 1 10 6 60 56

If you quickly go through these numbers you will find out that they repeat. When the “10” appears for the second time it starts to repeat. (I also forgot to say that if there is negative number it will act as positive on the “swap” step.) For some reason, many of these “constants” that I start with, end in lapses of “tens” meaning that after “-1” there is “10” and then that is the cycle until new “10” appears. First few numbers have the length of the cycle or lapse “36” or “12” and so far, there seems to be only “1 and 10” as constants that will pull it down to zero. (Also 100 but that is trivial and I have not checked some that could be obvious.)

I have made a program in Delphi 7 to write for me all the numbers for any given constant, that is useful but I will still have to consider the mechanism itself to start to understand it.

Dragallur