Can Rare Earth Magnets Lift a Moving 200,000 lb Object?

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Discussion Overview

The discussion revolves around the feasibility of using rare Earth permanent magnets to lift a moving 200,000 lb rectangular object, exploring both practical applications and theoretical considerations.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • Some participants suggest that placing a magnet under each corner of the object could enable lifting it.
  • One participant humorously proposes using larger magnets to lift the object from the top instead.
  • A participant provides a link to a neodymium magnet pull force calculator, indicating its relevance to the discussion.
  • Another participant questions whether the repulsive force of a magnet is equal to its attractive force, referencing the calculation of magnetic energy density.
  • There is a technical explanation regarding the calculation of magnetic forces based on energy density and spatial derivatives.

Areas of Agreement / Disagreement

Participants express differing views on the practicality of lifting the object with magnets, and there is no consensus on the effectiveness of the proposed methods or the relationship between attractive and repulsive forces.

Contextual Notes

The discussion includes assumptions about the strength and configuration of the magnets, as well as the nature of the object being lifted, which may not be fully addressed.

tj111
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Hello. I'm new to the forum and I hope this is the correct place for this question. Would it be possible to lift a 200,000 lb rectangular object that is in motion using rare Earth permanent magnets at each corner?
 
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Yes. Place a magnet under each corner and lift away.
 
GRDixon said:
Yes. Place a magnet under each corner and lift away.

Rofl. Or get big enough magnets and lift from the top.
 
Thanks Bob. I will check that out.
 
Hi Bob, Thanks again for your response. I checked out the calculator. My next question, being that the calculator dealt with attractive force, is the repulsive force of a magnet equal to the attractive force of a magnet?
 
tj111 said:
Hi Bob, Thanks again for your response. I checked out the calculator. My next question, being that the calculator dealt with attractive force, is the repulsive force of a magnet equal to the attractive force of a magnet?
The repulsive force of two same-polarity magnet poles is due to the spacial-derivative of the total magnetic energy (magnetic energy density integrated over all space):

W = 1/2 ∫B·H dVvolume

The force along x is then

Fx = dW/dx

This is the same force that attracts a magnet to a steel plate, at least it is calculated in a similar way.

Bob S
 

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