Magnetic force applied over long distances in fantasy book

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Discussion Overview

The discussion revolves around calculating the magnetic force required to levitate a person and launch objects in a fantasy context, specifically inspired by the book "Mistborn." Participants explore the implications of magnetism as a force in this fictional setting, including its application over distances and the mechanics involved in lifting weights.

Discussion Character

  • Exploratory
  • Conceptual clarification
  • Debate/contested
  • Mathematical reasoning

Main Points Raised

  • One participant seeks to determine the magnetic force needed to levitate a 100lb person 100ft above a steel plate, questioning how weight and distance affect the required strength of the magnetic force.
  • Another participant questions the feasibility of using magnetism in the context of the fantasy book, suggesting that if it is fantasy, the mechanics of magnetism may not need to apply.
  • There is a discussion about the nature of magnetic forces, with one participant suggesting that the strength of the magnetic pull would decrease over distance, prompting questions about how to calculate this decay rate.
  • Clarifications are made regarding the behavior of magnets, including that they attract iron rather than repel it, and the potential relevance of electromagnets in this scenario.
  • Participants express uncertainty about the mechanics of magnetic forces in the context of the fantasy setting, with one participant acknowledging confusion in articulating their questions.

Areas of Agreement / Disagreement

Participants do not reach a consensus on the application of real-world magnetism to the fantasy scenario. There are competing views on whether the principles of magnetism should apply and how they might be interpreted in a magical context.

Contextual Notes

The discussion includes assumptions about the nature of magnetic forces, the effects of distance on force strength, and the characteristics of materials involved, which remain unresolved. The relationship between weight, distance, and magnetic force is also not fully clarified.

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TL;DR Summary: Determine a newton force equivalent at the base of the magnet to suspend an object in the air with magnetism

In a fantasy book series I enjoy reading, one of the powers the characters have is very similar to magnetism. They are able to pull and push metal objects to/away from them.

I'm going to be taking some liberties so that it will hopefully be calculable and still translate to the book as close as possible.

The feat they perform that I specifically would like help with is that they are able to levitate around 100ft off the ground if they have an anchor directly below them.

So the scenario that I would like help in calculating is as follows.

Assuming that the magnetic force is all being applied from the feet, how strong of a magnetic force (gauss?) would be required to hold a 100lb person 100ft off the ground if there is a steel plate underneath them that is being used as an anchor? And how much force would that be able to launch something, such as a steel ball that is only a couple ounces?

I doubt it would be as clean as I would like, I would really like to be able to look at different weights and distances to see how it would impact the strength required. For example, a 200 pound person 150 ft in the air. The height is for of I have the distance wrong, but I'm especially curious about the weight because the weight of a person affects the strength of the force they can output, so a 100lb person and 300lb person could both levitate 100ft in the air.

I've been doing a lot of research, and I first asked a really poorly worded version of this on Reddit that didn't give the answer I needed (because I asked the wrong question, their answers for my bad question were accurate). But after asking that, and then doing a bunch of research on my own that has been fruitless, I thought I'd come here. The physics subreddit encouraged using a forum for a more in depth question.
 
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Hello! Just to meet the requirements for this forum, which I moved the thread to, what is the fantasy book?
 
Greg Bernhardt said:
Hello! Just to meet the requirements for this forum, which I moved the thread to, what is the fantasy book?
It's called Mistborn. And thank you. I wasn't sure since I was referring to a magical book, but at the same time asking a science question about it.
 
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(1) Magnets don't really work that way.
(2) If it's fantasy, why use magnetism when you can use magnets?
 
(1) How do you mean "they don't work that way"? Do you mean that the strength of the magnetic force wouldn't change how much push/pull it has at longer distances?
(2) I'm just interpreting it as magnetism because it seems like the most relative real world force, and it only affects metals. Although it doesn't take into account if they are ferrous or not, I figure it's the closest I'll be able to get for determining the strength.

If I'm understanding right, say there was a horizontal tube with a metal ball at the bottom of it. If I slowly lowered a magnet down, as soon as the pull of the magnet was able to overcome the force of gravity, the ball would go up to the magnet. If I had a stronger magnet, then I assume it would pull the ball up sooner. I'm wondering about the decay rate of that force so that I can calculate how strong the initial pull would have to be to lift that metal ball 100 ft off the ground (well, technically push that metal ball 100ft off the ground but I'm also assuming that pulling it off the ground vs pushing it off the ground would require relatively the same amount of magnetic force).

I'm sorry if I'm not being clear on what I'm trying to figure out. I may, in my attempt to be clear, instead be giving a word salad that's impossible to sift through


Edit

I think I know what you are saying about "magnets don't work that way". Would it be because the size of the magnet directly affects the strength of the pull? Would electromagnets be a closer analogue?

Double edit
Clarified by lbix - Thank you!
 
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QuantifiablyInvested said:
(1) How do you mean "they don't work that way"?
A magnet will always attract iron, not repel it.

The little of Sanderson I've read seems to have an unusually consistent magic system, but it's still magic.
 
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Thank you! Hopefully my pull example will lead me to the answer I need instead.
 

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