Spinning a top with assistance from a magnetic field

At the Brilliant office, we have a new toy that mysteriously arrived. It's a small black circular platform that comes with a tiny metal top. Our CTO Sam gave it a spin this morning, and here it is, at lunch time, still going:

Endless Spinning Top Endless Spinning Top

(click for video)

It looks like it has a battery inside, so we presume that there's some sort of electromagnet. Well, this got me thinking about the impossibility of perpetual motion. On a high level, you could say that the energy that is keeping the top from succumbing to friction and falling over is being supplied by the battery.

I presume that electromagnetism is somehow responsible. If the magnetic field supplied by an electromagnet can keep it going, could you do the same thing with the field created by magnetized iron? In other words, as iron gets magnetized, does potential energy go into it that can come out slowly over time in the form of (for instance) stabilizing this top, slowly demagnetizing the iron over time?

But this doesn't sit right with me. An unchanging field (magnetic or otherwise) should never be supplying energy, right? As I understand, it only defines which states are high energy or low energy, the path between the states should be irrelevant. So what must really be happening is that the electromagnet is creating a changing magnetic field, which is what is keeping this thing going. But then, by what mechanism might it be working? Perhaps it's like a motor, and the top isn't uniform metal.

Thoughts? Explanations?

Note by Dan Krol
5 years, 10 months ago

No vote yet
1 vote

  Easy Math Editor

This discussion board is a place to discuss our Daily Challenges and the math and science related to those challenges. Explanations are more than just a solution — they should explain the steps and thinking strategies that you used to obtain the solution. Comments should further the discussion of math and science.

When posting on Brilliant:

  • Use the emojis to react to an explanation, whether you're congratulating a job well done , or just really confused .
  • Ask specific questions about the challenge or the steps in somebody's explanation. Well-posed questions can add a lot to the discussion, but posting "I don't understand!" doesn't help anyone.
  • Try to contribute something new to the discussion, whether it is an extension, generalization or other idea related to the challenge.
  • Stay on topic — we're all here to learn more about math and science, not to hear about your favorite get-rich-quick scheme or current world events.

MarkdownAppears as
*italics* or _italics_ italics
**bold** or __bold__ bold

- bulleted
- list

  • bulleted
  • list

1. numbered
2. list

  1. numbered
  2. list
Note: you must add a full line of space before and after lists for them to show up correctly
paragraph 1

paragraph 2

paragraph 1

paragraph 2

[example link](https://brilliant.org)example link
> This is a quote
This is a quote
    # I indented these lines
    # 4 spaces, and now they show
    # up as a code block.

    print "hello world"
# I indented these lines
# 4 spaces, and now they show
# up as a code block.

print "hello world"
MathAppears as
Remember to wrap math in \( ... \) or \[ ... \] to ensure proper formatting.
2 \times 3 2×3 2 \times 3
2^{34} 234 2^{34}
a_{i-1} ai1 a_{i-1}
\frac{2}{3} 23 \frac{2}{3}
\sqrt{2} 2 \sqrt{2}
\sum_{i=1}^3 i=13 \sum_{i=1}^3
\sin \theta sinθ \sin \theta
\boxed{123} 123 \boxed{123}

Comments

Sort by:

Top Newest

What is especially confusing to me is that when you leave the top on the surface without spinning it, it is clearly laying on top of a magnetized surface, but it seems to be statically oriented (the top doesn't move around or point in different directions).

Silas Hundt Staff - 5 years, 10 months ago

Log in to reply

Question: Who is coughing in the background?

Finn Hulse - 5 years, 4 months ago

Log in to reply

Probably Bradan.

Dan Krol - 5 years, 4 months ago

Log in to reply

@Dan Krol Wait your lawyer goes to work at an office? I thought he just writes one paper and then he's done. :O

Finn Hulse - 5 years, 4 months ago

Log in to reply

Its a levitron toy. www.levitron.com/‎

A Former Brilliant Member - 5 years, 10 months ago

Log in to reply

Without referring to the site, though, how exactly does it work?

Silas Hundt Staff - 5 years, 10 months ago

Log in to reply

That got me all excited, but I tried it out and I sense no indication that it is supposed to levitate. The magnet is way too weak, I think it's a different sort of toy. The base looks different.

Dan Krol - 5 years, 10 months ago

Log in to reply

×

Problem Loading...

Note Loading...

Set Loading...