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> The top of the can is then added. This is carefully engineered: it is made from aluminum, but it has to be thicker and stronger to withstand the pressure of t
by bjornsing 12y ago
> The top of the can is then added. This is carefully engineered: it is made from aluminum, but it has to be thicker and stronger to withstand the pressure of the carbon dioxide gas, and so it uses an alloy with more magnesium than the rest of the can.
Nope, the pressure from the carbon dioxide pushes equally against all sides of the can. If anything the pressure at the top is slightly lower than at the bottom, at least if the can is standing, because of the weight of the coke pushing against the bottom.
- refurb 12y agoYou are correct, but I read that as "the weakest part of a can is the top and bottom, so it needs to be stronger"
- jonah 12y agoThe pressure difference is trivial. The reason it has to be thicker is because the top is flatter than the sides (convex) and bottom (concave). If the top was domed up it could be thinner. Have you ever seen an overheated or frozen can? The top is usually bulging while the rest is still intact.
- electromagnetic 12y agoActually most frozen cans have the bottom inverted, but I've only noticed this happen since about 2010. It used to be that a fully frozen can always used to blow.
- ladelfa 12y agoTop also needs to be stronger to handle the stress of the flip-top, which -- fun fact! -- starts off as a second-class lever and ends up as a first-class lever. http://crowdtube.tv/watch/pop-can-stayon-tab-slow-motion/ http://crowdtube.tv/watch/pop-can-stayon-tab-slow-motion/