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DPChallenge Forums >> General Discussion >> Amazing Circle Illusion
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Showing posts 1 - 19 of 19, (reverse)
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09/10/2014 12:30:10 PM · #1
Check this one out: every ball is moving in a straight line!
09/10/2014 12:57:12 PM · #2
What is this sorcery??
09/10/2014 01:24:50 PM · #3
basic tangential motion.
09/10/2014 03:43:54 PM · #4
Originally posted by Mike:

basic tangential motion.

Tangents are OUTSIDE circles, surely?



But I don't know much physics, so I'm sure there's more to it :-) Educate me?
09/10/2014 03:52:22 PM · #5
Now we're off on a tangent ;-)

The "illusion" is really basic geometry. It only works when the radius of the inner circle is exactly one half of the radius of the outer circle.
09/10/2014 04:59:53 PM · #6
definitely interesting :)
09/11/2014 07:34:04 AM · #7
Originally posted by Bear_Music:

[/img]

But I don't know much physics, so I'm sure there's more to it :-) Educate me?


a tangent is a line that is perpendicular a radial line of a circle. if you whirl a ball on a string around your head and let go the ball fly's off on a line tangent to the circular motion, as in your diagram.

Like kirbic said, if the geometry is right, you can time the movement of the circles on the lines so that they appear to be a spinning circle inside a larger one. actually if you plot points on rotating objects you get all sorts of interesting patterns and they move relative to their surrounding all the time.

i'll see if i can post some pics later..

Message edited by author 2014-09-11 07:36:18.
09/11/2014 11:10:54 AM · #8
Originally posted by Mike:

... if you plot points on rotating objects you get all sorts of interesting patterns ...

Check out the old "toy" the SpiroGraph® for amazing examples ....
09/11/2014 11:16:59 AM · #9
Originally posted by GeneralE:

Originally posted by Mike:

... if you plot points on rotating objects you get all sorts of interesting patterns ...

Check out the old "toy" the SpiroGraph® for amazing examples ....


We still have two of the "Super Spirograph" sets in original boxes, with almost all of the original parts.
09/11/2014 12:19:25 PM · #10
Ah! Spirographs!! I still remember the red, green, yellow, and blue pens!
09/11/2014 01:32:17 PM · #11
Originally posted by kirbic:

Originally posted by GeneralE:

Originally posted by Mike:

... if you plot points on rotating objects you get all sorts of interesting patterns ...

Check out the old "toy" the SpiroGraph® for amazing examples ....


We still have two of the "Super Spirograph" sets in original boxes, with almost all of the original parts.

You are now a candidate for Antiques Roadshow ... though it's somewhat sad that the boxes are almost surely by far the more valuable (monetarily) component ...

Online Spirograph

Message edited by author 2014-09-11 13:33:34.
09/11/2014 09:37:22 PM · #12
I had a Spirograph set growing up. It was one of my most favorite toys for years and years... and years. It wasn't a "Super Spirograph" though, and the box was most certainly destroyed.
09/11/2014 10:11:35 PM · #13
Originally posted by tanguera:

Ah! Spirographs!! I still remember the red, green, yellow, and blue pens!


You know, I think I remember those, too. Very vaguely, but I remember them.
09/11/2014 10:16:33 PM · #14
Me also. I loved the spirograph. Though I think I was older when it showed up... Or do they date back to the Neolithic?
09/11/2014 10:26:27 PM · #15
Originally posted by Bear_Music:

Me also. I loved the spirograph. Though I think I was older when it showed up... Or do they date back to the Neolithic?

1965 for that brand according to Wikipedia, but the concept/prototypes appear to go back to the 1800s ...
09/12/2014 10:52:41 AM · #16
Originally posted by GeneralE:

Originally posted by Bear_Music:

Me also. I loved the spirograph. Though I think I was older when it showed up... Or do they date back to the Neolithic?

1965 for that brand according to Wikipedia, but the concept/prototypes appear to go back to the 1800s ...


Yep, that seems about the right timing. I was six, and I remember seeing the ads and being enthralled. We got one as a Xmas gift, and I think my Dad got as much fun out of it as we did! He produced some beautiful stuff. We spent hours and hours with that thing.
A few years later my brother and I both got the "Super Spirograph" version, and that set us on anther round of creative madness. IMO one of the great toys of all time.
11/25/2015 01:02:26 PM · #17
Light-Painting Spirographs Tutorial ... too bad I don't have Bulb mode ...
11/25/2015 03:43:41 PM · #18
Originally posted by GeneralE:

Light-Painting Spirographs Tutorial ... too bad I don't have Bulb mode ...


Here is one I played with a while ago:

11/26/2015 08:32:47 PM · #19
this is not an illusion. the balls are moving in straight lines and they are *also* moving around the circumference of a moving circle.
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