August 19, 2004

Sink or Float?

So, how good are you at comparing an object’s density to the density of water? A friend recently mentioned that David Letterman sometimes has a “What Floats?” segment. My kids do that, too, although they don’t have their own TV show.

We here at Dr. Momentum Labs are not to be outdone. So I have this little thought experiment for you. I have placed a number of different cans of beverage into a tub of cool tap water and noted their buoyancy. You lot, if you wish, get to guess what I saw, and why I saw it.

Here are the items I tested:

  1. a 12 oz. can of Coke (not pictured)
  2. a 12 oz. can of Diet Coke w/ Lime
  3. a 12 oz. can of C2 (half the sugar of regular Coke)
  4. a 12 oz. can of ginger ale
  5. an 8 oz. can of ginger ale

So, masters of the world of physical knowledge… what did I see? No fair trying the experiment yourself and reporting your results. If you’re going to try it, register your guesses first, and your reasoning. I’ll post my observations on Saturday.

Posted by James at August 19, 2004 10:56 PM
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hmm, i wanna say they all sunk, but I seem to recall when getting a soda out of a cooler once, I think some cans were floating...and btw that's a tiny can of Canada Dry, i've never seen that before.

Posted by: steamynachos at August 20, 2004 1:18 AM

I'm guessing that they all did the same thing because they are all mostly water. I would guess that they floated because with the air and CO2 they would be less dense (I am thinking the can probably doesn't do much to the buoyancy one way or another).

The Diet Coke would be most likely to float and either the regular Coke or the 12 oz can of GA would be most likely to sink because corn syrup is denser than water.

The 8 oz can of GA would be less likely to sink than the 12 oz can because (again, I am just assuming) the ratio of empty space in the smaller can would be more significant.

I'm too lazy to try it myself. I'll take your word for it. :)

Posted by: Julie at August 20, 2004 9:26 AM

Without having a clue about this my guess is that they all float. Or if one sinks, it would be the tiny Canada Dry can.

Posted by: Mike at August 20, 2004 11:38 AM

Forgive me for metagaming, but I feel James wouldn't have bothered posting this unless something unexpected happened. Thus I have a funny feeling that not all of the cans did the same thing.

Canada Dry is sometimes sweetened with corn syrup and sometimes with sugar (and by the way, sugar sweetened tastes better). So if corn syrup made the difference it would be hard to tell, except I think the corn-sweetened Canada dry cans have gold-colored tops, and the sugar sweetened have silver-colored tops. Don't ask me how I know this, it's just a theory. So based on that little theory I'm going to guess that maybe the little can (silver) floated and the big can (gold) sunk.

I figure can size shouldn't make much difference, but I'm going to guess the contents were chemically different.

As to the others, Coke, Diet Coke, and the seething cylinder of vile crud that is C2? No idea. They may have ingredients in them which are heavier than water, but they also have CO2 which is much lighter, and in addition some of the water in them has been displaced by other substances. Furthermore there's no guarantee that the CO2 to fluid ratio is identical in the sodas and no other way really to tell except to test them oneself. One hint would be to weigh the large cans I suppose, but that would also be cheating. So I guess all I'm left with is intuition. My intuition says the Coke floated while the Diet Coke and the Coke-Teyewww sank.

Okay Burkie, you've been called. Let's see the cards...

Posted by: Chuck S. at August 20, 2004 1:22 PM

To be honest, I jsut grabbed what was in the fridge. Your metagaming does make sense, though, because I thought of doing this based on what I saw a few years ago at a science presentation for kids that the university does for free each year.

Posted by: James at August 20, 2004 1:58 PM

Well? Some of us would like to know the answer, please.

[tap tap tap]

Posted by: Patti M. at August 20, 2004 2:51 PM

I said I would post them on Saturday.

Posted by: James at August 20, 2004 3:15 PM

Damn. We'll be in Montreal. We'll just have to wait!

Posted by: Patti M. at August 20, 2004 3:17 PM

You'll be distracted for your entire trip! You could always repeat the experiment. :)

Posted by: James at August 20, 2004 4:28 PM

Diet Coke
Canada Small
Canada Dry

Diet Coke has no sugar.. so it has less dissolved solids in it.
I think the small Canada Dry one would be higher than regular since the can is in a more optimal size and there would be less wasted metal.
In addition, the air gap from the top of the can would be a higher ratio than the regular can.

The C2 has half sugar.. so its has less dissolved solids

I believe canada dry has more fizz than coke.. so it would be lighter than coke.

Posted by: poo poo head at August 20, 2004 9:42 PM

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