Is the Magnetic Field Doing Work When a Magnet Sticks to a Metal Wall?

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Discussion Overview

The discussion revolves around whether a magnetic field does work when a magnet adheres to a metal wall. Participants explore the concepts of work in physics, particularly in relation to magnetic forces and the conditions under which work is defined.

Discussion Character

  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • One participant questions if the magnetic field is doing work when a magnet sticks to a metal wall, suggesting it might be rearranging elementary particles to create attraction.
  • Another participant argues that, similar to a peg holding a hat, the magnet does not do work because there is no movement involved.
  • A participant points out that work is defined as force multiplied by distance, questioning where the distance is in this scenario.
  • Another participant introduces a hypothetical scenario with a plastic material between the magnet and the wall, asking if the magnet is doing work in that case.
  • Responses clarify that force applied at a distance does not equate to work done, emphasizing that work requires displacement.
  • One participant explains that holding an object at a constant height does not involve doing work, contrasting biological and mechanical systems.
  • Concerns are raised about common misconceptions regarding magnets as potential energy sources, with references to perpetual motion machines and gyroscopes.

Areas of Agreement / Disagreement

Participants generally disagree on whether the magnetic field does work, with multiple competing views presented regarding the definitions and conditions of work in physics.

Contextual Notes

Participants reference the need for displacement in the definition of work and discuss the implications of misunderstandings related to energy sources, but do not resolve these issues.

Crazymechanic
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Hi

a simple question that struck my mind.Let's imagine a ferrite magnet from a old loudspeaker now let's put that magnet on a metal wall , or door , the magnet holds to the metal vertically and any other material put similar would just fall off so t seems to me that the magnet or the magnetic field is doing work.
So is this true that the magnetic field is doing work or is it wrong , is the magnet just arranging elementary particles in such a way that let's those two physical objects attract each other like opposite charges attract one another?

Tahnks.
 
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Hi Crazymechanic! :smile:

If I hang my hat on a peg on the wall, the peg stops the hat falling, but the peg does no work. :wink:
 
Hmm interesting answers.Ok Russ I let's assume we have a 5cm thick magnet and 5cm thick metal door, let's put a 1cm thick plastic material between the metal door and the magnet is now the magnet doing work? because the magnet is still holding on but at a distance away..?
 
No: That's force applied at a distance, not through a distance. The "distance" in the work equation is the distance the object moved.
 
"through a distance" aka "displacement".

Compare a fridge magnet to a book shelf. Neither is moving (zero displacement). Neither is doing any work to hold itself up. Neither needs a power source.
 
This is a very important concept in physics...

If you hold a heavy book out at arms length (constant height) your body is doing no work on the book because the book is not moving. It doesn't feel like that because of the way the body works - it's is a biological machine. Were it a machine made of say metal or wood no power would be required to hold it still at a constant height (such a machine is called a bookshelf).

Large numbers of people missunderstand this issue. As a result they think magnets are a potential source of energy and try to build perpetual motion machines from them. They are wrong.
 
CWatters said:
Large numbers of people missunderstand this issue. As a result they think magnets are a potential source of energy and try to build perpetual motion machines from them. They are wrong.

Or Gyroscopes.
Gyros are very popular with the loony fringe.
Gyros AND magnets now... :D
 

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