Now you know

Why do aluminum beverage cans have concave bottoms? No, it's not a trick to make you think you're getting more than you are. The aluminum walls of a carbonated beverage can are only .005 in. thick - about as thick as a magazine cover. The walls can be so thin because the pressure of the carbon-dioxide gas stiffens the walls the same way a flabby balloon is stiffened when it's filled with air. That's also why the can bottom can't be flat: The pressure would push it out, and the can would rock on its bottom. The concave bottom acts like an arch dam to resist the pressure. The top can't be dished, though, so it has to be thicker - which is why the cans have a "stepped neck": a smaller-diameter top uses less metal.

Source: 'The Evolution of Useful Things,' by Henry Petroski (Henry A. Knopf, 1992)

You've read 3 of 3 free articles. Subscribe to continue.
QR Code to Now you know
Read this article in
https://www.csmonitor.com/2005/0408/p18s02-hfgn.html
QR Code to Subscription page
Start your subscription today
https://www.csmonitor.com/subscribe
CSM logo

Why is Christian Science in our name?

Our name is about honesty. The Monitor is owned by The Christian Science Church, and we’ve always been transparent about that.

The Church publishes the Monitor because it sees good journalism as vital to progress in the world. Since 1908, we’ve aimed “to injure no man, but to bless all mankind,” as our founder, Mary Baker Eddy, put it.

Here, you’ll find award-winning journalism not driven by commercial influences – a news organization that takes seriously its mission to uplift the world by seeking solutions and finding reasons for credible hope.

Explore values journalism About us