# Sand pendulum

Sand pendulum

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Thank you for posting the full vid from /r/gifsthatendtoosoon

2. TheDarkForrest says:

What kind of effect would the speed of the sand leaving the glass have on the way it moves? Like would the decrease in mass change anything?

3. mandressedlikeabat says:

I dare say that /r/oddlysatisfying would show this some love too.

4. idesofmayo says:

I don’t understand why the ellipse changes to a circle and then to another ellipse.

5. Benjyjf says:

It’s called a lissajous curve. It’s best defined as a parametric function. An example is x=cos(5t) , y=sin(7t)
EDIT: link to example. Try editting the coefficients (the 5 and the 7) to see different examples. Generally, the larger they are, the closer to a square it gets.
https://www.desmos.com/calculator/aenq9gbrcq

6. drakulaboy says:

hypnotizing

7. deepwatermako says:

So this was extremely peaceful

8. Beatle7 says:

Damn. I wanted to see it end.

9. SpellsThatWrong says:

/r/oddlysatisfying

10. WillsMyth says:

Couldn’t you use this to calculate the rotation of the earth? I thought I read that in the “stick in the mud physics” chapter of death by black hole.

11. CronosDage says:

did this with paint the other day

12. SomeGoodInThisWorld says:

That’s awesome

13. somegal09 says:

Transformational

OK, someone please explain why the pendulum moves the way it did. Someone has to be controlling it right?

How does it gain and lose momentum in different directions?

15. TurboHertz says:

Reddit gold to whoever finds the parametric equations for this.

16. Boniferous13 says:

Excuse me, gif. I wasn’t done watching

17. oxygenvoyage says:

Would love to see more sand pendulum gifs in this sub very cool

18. LasagnaMuncher says:

It looks like a double-sided coma astigmatism.

Edit: Oops, I meant coma aberration.

19. Sirsarcastik says:

I’m hypnotized

20. RyanTheCynic says:

That was awesome

21. Airowan says:

SAND CROISSANT

22. Roccobot says:

This is fucking amazing

23. hts671 says:

Is it drawing a fractal?

24. Murmaider13 says:

I knew it. The eye of fucking sauron again.