# Physics experiment - Infinity marble-run spiral

in design •  8 months ago

## Have you ever wondered if it is possible to build a #marble-run that lasts forever! I am working on a little experiment to see if it is possible.

The idea is simple, build a spiral and rotate it fast enough in opposite direction to the marble so that the marble will never reach the end of the spiral. I believe as long as I match the speed of the marble in opposite direction, this experiment should work.

Based on that idea I started a #marble-run design in fusion360 that I will print in the coming days (if possible due to the complex shape) to give it test run. The design consists of two parts, a base that will hold a ceramic bearing and the spiral track track. Initially I will rotate the spiral manually to see if I can keep the marble from reaching the end. If it works and I can determine the needed speed, I like to add a little motor that will rotate the spiral going forward and basically let the marble run until you plug the power.

## Imagine what a cool sight that would be on your desk!

If you have ideas or recommendations on how to improve this #marble-run design than please let me know or even better, write a steemit post with your own cool idea using the marble-run tag! Lets create some cool designs on steemit that might attract new designers!

If this works as I hope it does I will upload the file on Thingiverse for free download and present it at my son's school. This would be a great showcase I think for children to explain physics and show it in a fun way.

All the best!

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I really like this idea, I think it will be a beautiful physics demonstration. One detail I'd like to point out is that while the marble will stop in-place, unfortunately it won't continue to roll in-place. You can easily reduce this experiment to 2 dimensions to see what I mean (see gif):
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The friction between the marble and the surface of the track will prevent the marble from maintaining its rotational momentum as it stops descending the track. Interestingly, in a sort of catch 22 the marble would never begin to roll in the first place without this friction, it would simply slide down the track without rotating.

That being said, I think this will be a really cool demonstration either way. Looking forward to seeing updates!

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Luckily, centripetal force will help out a bit here, too. Because the marble wants to keep moving in a straight line but can't because it's contained on the side, friction will be increased against some portion of the bed somewhat away from straight down and greater than the raw force of gravity.

Which is great, because it means that the window of rotational speed for the helix is slightly wider than it would be otherwise.

I don't I envy anyone the challenge of finding just the right speed to make this work, but that speed exists. In fact, it is nontrivial but possible to spend the helix at an adjustable rate which would because the ball to go up and down the trough at an adjustable rate, as someone else said they'd like to see.

This could be very interesting.

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Great point! The fact that the normal vector won't be straight down as it runs around the helix may be advantageous. Though I said that the marble wouldn't spin in place, it's possible that it could temporarily if the track was composed of two materials with two different friction coefficients (see sketch of track cross section):

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It seems you are very much into physics and I am happy you find this little experiment interesting.

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It's not so much that I'm into physics as it is that physics is just one of the things that is into me.

If only it were different!

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I love the detail and gif you put in your comment, thank you for that. I try to print out the spiral this weekend and if successful will post the results. Thanks again.

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No problem. Your design is really creative, I hope the print turns out well.

Sounds like a real fun projekt. Right now from your design it seems to be very difficult to print due too the overhang. If you reverse it and make it smaller at the top and larger at the bottom you can put sturctures below the runway and print it easier. Just my 2 cents.
From the speed point of view I don’t see a problem. You just need to find the right motor.

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Great feedback, I see that you know your 3d stuff ;-). Exactly that is why I am a bit cautious in my post since I am not sure if a 3d print will work. One more reason to get a printer with dual extrusion so I can use desolveable filament for overhang and support. Thanks again.

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Oh, well that's a great idea. Hopefully you manage to make it work. I would really like to see this in action!

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Yes, I try to print it this weekend and see how it goes :-)

This would be completely awesome and I would like to pre order one haha !

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yes if this works I will send you one :-)

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That would be amazing :) Looking forward to see how it will work in real life :)

wow..this is superb.. you are a very creative one..good job :)

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Thank you very much.

I am quite impressed with your idea and really want to see the final printed design. When you will give a high speed, I really want to see how will it look like?

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Thank you! I will provide an update soon.

Outstanding design. What a creativity!

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Thank you very much!

Wow ... That's a really amazing piece of work. I will try to make it. Hopefully I can do very well. Can imagine the beauty and uniqueness of the object is located on the table. Good luck always for you @tarekadam.

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Yes, I am curious if it works. Glad you like it.

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Good luck with perfect. I am also happy. 👍

A thought I has was what if the inside surface of the track had more and more friction as it got lower and lower - this would keep it from going so fast as to hit the bottom, as it might be hard to find the sweet spot...

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That is a great thought and also something I thought about. For the moment I try it without much friction on the surface but if I need to rotate it too fast than I might add in some friction.

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Another thought: second prototype maybe - it would be neat in my opinion if the ball rolled down and up the track - the upper part could be more steep and the bottom could have more friction, then maybe it could have some travel - I love things like this- keeps the brain sharp! I am really curious how it will turn out!

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I love it too. Good suggestion!

so nice creativity ......you are outstanding..........some people have god gifted power,,,,,,,,you are one of them.......otherwise you can't.....keep it up,,,,,, best of luck

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Thank you very much.

thank you for sharing the information

this is a very cool thing to make looks very nice and interesting let the ball roll :D

cool concept and it will look nice to have as a decoration too

Seems like a great idea buddy and moreover it sure will great on my desk ;)
Best of luck with the project of infinity ball of roll !

That's an interesting idea:) Let us know if it works.

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Will do :-)