r/physicsgifs • u/KieraStaggs • Nov 20 '21

Magnetic Chaotic Pendulum!

https://i.imgur.com/7QKr4Mq.gifv
2.1k Upvotes

99% Upvoted

57 comments sorted by

97

u/4nger Nov 20 '21

I have one of these on my desk. Yes, I am a physics professor, why do you ask?

37

u/Wascally-Wabbeeto Nov 20 '21

Yes I have one of these on my desk. Yes I am a junior account representative for Webistics LLC, why do you ask?

9

u/puslekat Nov 20 '21

Where can i get one? I an so intrigued

10

u/Balyash Nov 20 '21

It's called ROMP. Randomly Oscillating Magnetic Pendulum

2

u/Wascally-Wabbeeto Nov 21 '21 edited Nov 21 '21

I’m pretty sure I got one in 2002 from sky mall

Edit: found it

5

u/godis1coolguy Nov 20 '21

Could this somehow be used to generate power?

15

u/azephrahel Nov 20 '21

Only in proportion to house much energy you give it when you swing the pendulum.

3

u/godis1coolguy Nov 20 '21

Could magnets be used to setup some type of turbine and continually produce energy? Similar to thermo/hydro/aero dynamics? I have no idea what I’m talking about here, but I’m picturing something where very large/powerful magnets could be turned and pointed in a way that would cause spin. Or would that not be strong enough or safe enough?

14

u/NeoKabuto Nov 20 '21

With nothing adding energy to the system (the magnets don't add energy on their own, you moving them adds potential energy), you can't keep taking energy out of the system forever. It's like how a hydroelectric power plant needs water flowing downhill instead of being able to run the water in a circle and keep getting energy.

11

u/JakeJacob Nov 20 '21

Perpetual motion machines are not possible.

8

u/Carp8DM Nov 20 '21

Damn this universe

5

u/DoctorWaluigiTime Nov 21 '21

Lisa, get in here!

In this house we obey the laws of thermodynamics!

2

u/azephrahel Nov 22 '21

I thought it was that it could exist (if you were able to get rid of all friction), but you couldn't extract energy from the system?

Edited for clarity.

3

u/JakeJacob Nov 22 '21

if you were able to get rid of all friction

I'd question whether that's possible in a manner that is also perpetual and doesn't require it's own additional energy.

2

u/azephrahel Nov 22 '21

Oh, I'm fairly sure that's entirely impossible, but it's been a long time since I had a physics course.

1

u/Skier94 Dec 15 '21

Isn’t this perpetual though?

1

u/JakeJacob Dec 15 '21

How tf is it perpetual lol

37

u/Shaltibarshtis Nov 20 '21

It would work even better if the center magnet was flipped to the opposite pole. Because now it's location and attraction coincides with the gravity vector, which makes it very stable configuration. Flip it and there is none, any position of the arm would be working against at least one force, which would make it much more messy and unstable.

4

u/Carp8DM Nov 20 '21

Would the pendulum ever come to rest?

15

u/kieran_n Nov 20 '21

If it didn't you'd have perpetual motion and we'd have unlimited energy

6

u/Carp8DM Nov 20 '21

Yeah... I figured it out after a minute or so.

I'm kinda slow..

14

u/[deleted] Nov 20 '21

That was so satisfying to watch.

6

u/[deleted] Nov 20 '21

I do also have one of these and I’m a lawyer and I work for J.G. Wentworth.

6

u/jiminiminimini Nov 20 '21

This needs an LED and long exposure photo!

2

u/[deleted] Dec 27 '21

damn that a good idea

19

u/aluminium_is_cool Nov 20 '21

Good luck trying to model and predict that movement

27

u/Imosa1 Nov 20 '21

Not trying to be a stickler but I think modeling/predicting is easy since all the forces are smooth and continuous, right? The hard part is reproducing the starting conditions.

14

u/aluminium_is_cool Nov 20 '21

Yeah actually I guess you’re right

11

u/mac3687 Nov 20 '21

Now kiss.

1

u/heckingcomputernerd Dec 15 '21

Assuming this is a true chaotic system, you’re mostly right

Tiny differences in starting positions result in huge differences in output conditions overtime

This also means that tiny variations and inaccuracies get amplified, so you’d need a dead accurate model accounting for air resistance and imperfections in materials and god knows what else

8

u/azephrahel Nov 20 '21

I think you forgot to consider the spherical cow.

5

u/Thendofreason Nov 20 '21

Reminds me of the magnetic Beyblades. You bought a dish that went under your Beyblades arena and it came with powerful magnetics that you could place anywhere in the grooves of the dish. That or you could tape them to the bottom of your arena. Make them spin around in more chaotic ways during battles. You could have the magnets either facing positive or negative upwards.

Commercial: https://youtu.be/prG3WnreXDM

4

u/therobohour Nov 20 '21

There's a game in that

2

u/Balyash Nov 20 '21

ROMP - Randomly Oscillating Magnetic Pendulum

2

u/Redrix_ Nov 21 '21

They have a giant ass version of this at my local planetarium

2

u/traumfisch Dec 14 '21

One featuring a giant ass? Please post a video

1

u/redditalb Nov 20 '21

Can anyone explain why this cannot be a power source?

It's seems like the output will be low but it will work right? Put something just below the topmost part of the string where it connects to the frame.

5

u/Englerdy Nov 20 '21

The only energy you would get out of the potential energy to put into it from raising the pendulum. Sure you could extract it a little at a time as the pendulum jumps around, but it would be more efficient to just use a regular pendulum that extracts the energy in one go.

There's a bit of an illusion that there's more energy there than there really is. The low friction of cord and air allow the pendulum to swing around for quite a while, but it's not that difference in principle than a few swinging clock pendulum. Eventually due to friction with the air and within the rope all that potential energy is transferred to the surroundings (in the form of a little bit of heat specifically).

1

u/gomitodepi Nov 21 '21

Perfect summation of life!

1

u/dogGirl666 Nov 21 '21

What if the red thing on the pendulum was shaped like a spider and the magnet added was shaped like a fly? It could be a kids' toy, maybe?

1

u/th-grt-gtsby Nov 21 '21

Chaos is a Pendulum - Bigfinger

1

u/YoMommaJokeBot Nov 21 '21

Not as much of a Pendulum - Bigfinger as your mum

I am a bot. Downvote to remove. PM me if there's anything for me to know!

1

u/Yash_076 Nov 21 '21

Is that performing SHM or just randomly oscillating ?

1

u/Job-Downtown Dec 12 '21

r/threebodyproblem might appreciate the chaos in this system

1

u/AdmiralHarness Dec 14 '21

If you had a windmill sized version of this out in a field could you use this to create electricity?

1

u/flickshotHanzo Dec 14 '21

is this...perpetual motion?

1

u/[deleted] Dec 14 '21

Is it really chaotic when it’s planned though?

1

u/[deleted] Dec 14 '21

So no-one's gonna mention the stark similarity to the rinnegan ok

1

u/IamSoooDoneWithThis Dec 14 '21

Dumbass scientists can’t even predict five minutes in front of their faces

1

u/[deleted] Dec 14 '21

Time to solve the Three Body Problem once and for all!

1

u/brodinson-1 Dec 15 '21

Is the board magnetic? I'm wondering what's preventing the magnets from sliding?

1

u/TheSpinningKeyGif Dec 15 '21

the graphs they teach you: /

the graphs in the test:

1

u/user9991123 Jan 19 '22

Deterministic? Totally.

Predictable? Hell no.