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I once heard that because gold is so malleable, while also being very heavy; that if one were to stack several layers of bars on top of on another (like is so familiarly depicted in movies & TV), the shape of the ones on the bottom would be smushed down because of the weight of the ones on top and gold's high malleability. Is there any truth to this?

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I think that the image in one of our closed question calls the underling claim into doubt. Furhter, I think that as formulated this would be better on skeptics (if a notable instance of the claim could be found). There may be a good Physics.SE question in here, but I don't think we have it yet: far too vague. – dmckee♦ Oct 10 '12 at 20:52
@dmckee Well, there isn't really any requirement that a question be based on a correct claim for it to be valid here. I don't think it would be too hard to reword this as a physics question, e.g. "How large of a stack of gold would it take to start deforming the bars on the bottom?" or something to that effect. – David Zaslavsky♦ Oct 11 '12 at 16:22
It is clear that @John has answered the good physics question that exists here. I would really prefer for the OP to edit this post as a demonstration that they understand the difference, but re-opening... – dmckee♦ Oct 12 '12 at 15:03

1 Answer

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All you need to do is work out how much force it takes to crush a gold bar, then calculate how many gold bars need to be stacked up to apply this much force.

A standard gold bar is 7" x 3.625" x 1.75" and weighs 12.4kg. The yield stress of gold is 205MPa. The area of a standard bar is 0.0164m$^2$ , so the yield stress corresponds to a force of 3,360,000N applied over this area, and this is the weight of about 28,000 gold bars. So if you stacked up 28,000 gold bars you'd start squishing the bottom one. But this pile of bars would be over a kilometer high, so I suspect even Fort Knox doesn't have any squished bars. I'm willing to try the experiment if someone will supply with the gold :-)

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