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I have the following empirical observation: A certain food that I often eat has a shape roughly like a solid hemisphere. It has two stable equilibria when resting on a surface: One with the flat side down, and another with the round side down. When I pour this food onto a pan, typically more of the hemispheres end up lying round side down than flat side down.

Given what I know about granular media, it seems plausible to me that the distribution of hemispheres dropped from some height is a Boltzmann distribution with some effective temperature that might depend on the height.

Question: What, if anything, is anything known about the orientation distribution of falling granules?

Qmechanic
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  • Sounds like a testable experiment with a camera and some image processing software…. though I suspect that with enough height there is less drag with the round shape down if the particles are dense enough would influence the distribution. – UVphoton Jul 12 '22 at 01:15
  • Are you talking about a solid hemisphere? The center of mass of such an object is 1R/8 closer to the flat side than to the round side. It seems more intuitive that it would land more frequently on its flat side. – buddhabrot Jul 12 '22 at 01:18
  • Related: https://physics.stackexchange.com/q/141569/2451 – Qmechanic Jul 16 '22 at 05:29
  • Why would the flakes have a distribution of velocities? A distribution requires some way of exchanging energy via collisions. In this case the only exchange is with air via the drag force, which is different for different orientations. But why would this be a Boltzmann distribution? Spherical particles would fall with nearly identical velocities. – Themis Aug 05 '22 at 09:58

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