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I was browsing Amazon for magnetic hooks for my fridge and saw this diagram which surprised me because it is the opposite of what I would expect. Wouldn't the "Vertical" magnet be the weakest possible orientation? Why is it instead stronger than the "Horizontal" one? Would a 45° angle be stronger or weaker than the other two options?

I apologize in advance if this is the wrong place to ask this question, or if the answer is more related to the structure of the product than physics in a vacuum.

The image I was looking at

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    $\begingroup$ It probably has to do with the lever arm. In the horizontal config, the lever arm is small and in the vertical config the lever arm is big. (P.S., the only answer that is given at the moment, by Suzu Hirose, does not really make sense, at least to me, so you should stay tuned and see if a better answer pops up.) $\endgroup$
    – hft
    Commented Aug 16, 2023 at 23:48
  • $\begingroup$ @hft - why does friction not make sense? If there were no friction at all, the magnet on the vertical wall would slide downward regardless of how strong it was. $\endgroup$
    – Jon Custer
    Commented Aug 17, 2023 at 13:52
  • $\begingroup$ @JonCuster I'm not sure what you are referring to with your question about friction. $\endgroup$
    – hft
    Commented Aug 17, 2023 at 14:44
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    $\begingroup$ @hft - the force that holds the "horizontal" configuration magnet to the wall is friction. Even if the lever arm is zero, friction is still needed as the answer by Suze properly points out. A very large lever arm will pull the magnet off the wall, yes, but that is an additional limit, not the primary one. $\endgroup$
    – Jon Custer
    Commented Aug 17, 2023 at 14:47
  • $\begingroup$ @JonCuster I think you are referring to my comment about one of the provided answers. I only wrote that the provided answer does not make sense to me. This has nothing to do with friction. It has to do with unclear statements like: "the weight of the object is directly held in opposition to the magnet's force;" etc. $\endgroup$
    – hft
    Commented Aug 17, 2023 at 15:12

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With the vertical configuration the weight of the object is directly held in opposition to the magnet's force.

enter image description here

With the horizontal configuration the weight of the object is held against a friction force resulting from the force of the magnet against the surface.

enter image description here

In equations this is written as $\mu F$ where $\mu$ is called the "coefficient of friction" and $F$ is the force of the magnet. They can claim that the magnet exerts a force of about 30 pounds or 130 Newtons but they don't actually know what the coefficient of friction is, so conservatively they estimate it to be about $\mu\approx 1/3$ and claim that the magnet can hold about 10 pounds in the horizontal configuration.

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  • $\begingroup$ I get it, so i’m the horizontal one, you are battling the force of the magnet sliding down, instead of the magnet coming off. $\endgroup$
    – aks.
    Commented Aug 23, 2023 at 13:10

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