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I don't have a physics background; I assume there's some simple link to give me to answer this, but I don't know the terminology for it and so haven't been able to solve this.

The use case it to avoid having my TV put divots into my IKEA KALLAX.

Here's what my intuition tells me:

  1. The best shape to distribute the weight is a conical frustum, with the larger circle on the KALLAX, and the TV legs sitting on the smaller one.
  2. The frustum should have increasing density as its diameter increases.

Are the intuitions correct? I have the sense that a dense substance would distribute weight much better than a less dense one, but why?

My current solution is to use dense foam, which is an incredibly crude approximation of the frustum I'm talking about. How can I tell if it's useful?

Again, my intuition is telling me that there's a falloff curve such that, while nowhere along the foam, is the dispersed weight going to be zero, there's going to be a threshold such that there's no point in having the foam be as wide as it is without trimming.

legs

Jessy
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2 Answers2

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The answer by Asher is right. I just want to extend it a little. Your intuition is incorrect, the density does not matter at all. The total force that a leg makes on the surface is independent of the shape of the legs. What you can do is spread the force into a larger area to reduce the pressure at each point on the table. You can simply put hard enough disks under the legs, which will do the trick. You can imagine the disk as part of the leg. If they are glued or not (that is, if a disk is really a part of the leg) is irrelevant on the pressure that the disk makes on the table.

  • What is "hard enough"? (Note: "do and make" are different words in English, unlike most Romance languages, so the phrase is actually "do the trick".) – Jessy Aug 24 '20 at 00:44
  • you got me, lol. So I mean it does not bend under the pressure of the actual legs –  Aug 24 '20 at 02:37
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I think you may have been downvoted because this seems more like an engineering problem than a physics question.

I'm also a little confused about what you're asking. I think that the optimal shape to disperse the weight to prevent divots in your furniture is one that maximizes surface area incident on the furniture. For instance, a large flat disk that's hard enough that it won't break/bend.

AsherLantz
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  • It's an applied physics question, so it's applicable to either site. Your disk idea is the bottom of my frustum. – Jessy Aug 23 '20 at 22:40
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    But your ideas that the frustum needs to be conical, and it "should have increasing density as its diameter increases" are both irrelevant to fixing the problem. All you need is a flat plate which is stiff enough not to bend, to spread the load over a bigger area. – alephzero Aug 23 '20 at 23:05
  • Nothing is stiff enough to not bend. To be able to describe that is part of the theory I'm looking for. – Jessy Aug 24 '20 at 00:42