Nutty explanation. (Letters).I think "The Brazil nut effect The brazil nut effect is the name given to a phenomenon in which the largest particles end up on the surface when a granular material containing a mixture of objects of different sizes is shaken. In a typical container of mixed nuts, the largest will be brazil nuts. gets more jumbled" (SN: 11/17/01, p. 309) ignored the major reason that large particles <onlyinclude> This is a list of particles in particle physics, including currently known and hypothetical elementary particles, as well as the composite particles that can be built up from them. rise to the surface. The laws of inertia inertia (ĭnûr`shə), in physics, the resistance of a body to any alteration in its state of motion, i.e., the resistance of a body at rest to being set in motion or of a body in motion to any change of speed or change in direction of and momentum indicate that larger particles don't don't 1. Contraction of do not. 2. Nonstandard Contraction of does not. n. A statement of what should not be done: a list of the dos and don'ts. react as quickly as smaller particles do at the end of each back-and-forth shake of the container. This means there is a force for relative motion between different-sized particles. Just as a basketball will roll over a tennis ball when they collide col·lide intr.v. col·lid·ed, col·lid·ing, col·lides 1. To come together with violent, direct impact. 2. , so larger particles when they collide will tend, despite their weight, to ride up over smaller ones. The convection effect can also be explained by momentum and inertia. As the container stops at each end of the back-and-forth shake, the contents tries to keep on going, thus pressing against the leading side of the container. This leaves a slight gap at the trailing side, into which only small particles can fall. As for rising faster in a vacuum, it would seem that air probably has a cushioning or even binding effect. Remove it, and it becomes easier for inertia and momentum to work their magic. Richard S. Blake East Falmouth, Mass. |
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