why is the base of cans concave?

Answer 1

Support. If you're talking about a can of soda (the only can I can think of that has a concave bottom), it's to keep the can from exploding. A lot of pressure builds up in those cans, especially when their dropped. Observe taht next time you have a can you drop. Let it warm up, it'll get bigger. Anyways, if it was convex, the can might explode! If it's concave, the can pushes on the dome, putting pressure on the other parts of the can, thus making it stronger. Think about it this way. You have to hit a wall with a hammer and break it. Would it be easier to break it if the arc was facing you or away from you? Answer: Away. That's why the can's arc faces the inside of the can. It's harder to break. hope I helped! :)

Some others might see this as a marketing opportunity to sell a can which holds less soda.

Answer 2

Actually a protruding spherical shape is more efficient to resist the internal pressure, but another design requirement is that the can not fall over when set on it's bottom side. Ergo, the conCAVE bottom which produces a circular tangent line to any flat surface.

To everyone who thinks this is a neccessity to resist the pressure:
What about the TOP of the can! No one even mentioned that! the answer to this whole ? is that the can shape is driven by pure economics. The cheapest way to make it is by a process called impact extrusion, where a little pellet of aluminum is dropped into the bottom of a VERY strong and stiff cavity just the shape of the ouside of the can. Then a punch with the same (external) shape is slammed into the cavity. The aluminum is squeezed like toothpaste into the shape we're all familiar with.

After filling, the top is put on by a rolling process. It's made flat because the process is too expensive with any other shape, and to improve stackability for shipping. The flat top is strong enough (even with the scores in it to tear an opening) to resist any pressure from the carbon dioxide inside.

Answer 3

Plenty of answers regarding pressure changes. Here's my version of the same answer. I think the ultimate point is to maintain the flatness of the bottom of the can when the internal pressure rises so it sits flat even if the concave gets pushed out. Kinetic energy increases due to agitation, warmer ambient temperature both lower the solubility of a gas in a liquid. So the warmer water gets, the more carbon dioxide is released adding to the pressure. The other way the pressure can increase is due to the unique physical properties of water when close to freezing temps. When the temp varies from 4°C to 0°C within the same physical closed context, water increases in volume. So as temps go down in a refrigeration unit to freezing levels, and sometimes even fridges can drop to 2 or 3 degrees depending on their calibration, it will cause an internal pressure increase but this time due water expansion. I feel the concave might be there to solve those kinds of pressure problems.

Answer 4

If makinga spherical surface was the purpose, why not make a convex surface? Quite a few people were close. The concave is to help withstand pressure. How? Most cans are filled under pressure. What would happen if the pressure increased inside the can because someone dropped it or heated it by mistake. The contents would start expanding. If it is a flat bottom it might buldge a bit but wont have much space to expand into. If it was convex it will not have anywhere to go and will explode immidiately. If its concave, it has lots of area to expand into and hence the possibility of it exploding reduces. Gotcha?

Answer 5

because in the canning process high heat is used to insure no bacteria are alive. When things are canned and then covered immediately, the air inside the can is basically sucked out causing that concave shape. you should never eat anything out of a can that doesn't have that concavity. It was probably not canned correctly.

Answer 6

It's the same as champagne bottles.
They put a concave on the bottom of soda, and beer cans so that the natural pressure of the carbonated beverage doesn't push out or deform the bottom of the can.

Answer 7

The question isn't very sparkling. the actual image formed by using a concave reflect is often solid on a demonstrate and also you spot the image on the demonstrate. you may enable the image fall on your retina , yet then numerous the image focussing is performed by using your cornea and the adjustable eye lens. putting the interest into any interest of image formation fairly mucks up the easy optics that faculties educate..... do not imagine about the image interior the reflect - only imagine about the image formed on a demonstrate. until eventually you ensure to develop right into a watch health care professional.

Answer 8

most cans with concave bottoms are made that way because they contain pressurized or carbonated product in them the shape keeps the pressure from expanding the can.

Answer 9

Stackability

Answer 10

to resist the pressure of the carbonation pushing outward. it acts like an arch would in a building.