Science time

January 28, 2008

Science time

I heard this song recently called “We Only Read the Headlines” by Lazy Boy. This song has this british womam reading all these facts one after another. Some of them are intresting, like the average length of an erect penis being 5.3 inches, 4.2 if circumcised… 22% of the time a pizza would arrive faster than an ambulace, in great britain.. 5% of the population is gay.. 1 on 4 women have had a homesexual experience.. etc.. After hearing the song, one question remains: Are all these “facts” actually true? Many of them depend on pretty sketchy survey evidence, but one set of facts given was open to easy scientific investigation, and that’s what we’ve done: we did a real experiment and even wrote some things in a notebook, so it must be True. The fact as stated was that a can of Diet Coke would float but a can of normal Coke would sink. Easy enough to check out. I brought home some samples: 1 can of Diet Coke, 1 can of Coke Classic, and one can of Mountain Dew as a control. Before getting anything wet, i decided to take weight measurements. Here were the results: Diet Coke	367.5 g
Classic Coke	382.5 g
Mountain Dew	392.6 g

I heard this song recently called “We Only Read the Headlines” by Lazy Boy. This song has this british womam reading all these facts one after another. Some of them are intresting, like the average length of an erect penis being 5.3 inches, 4.2 if circumcised… 22% of the time a pizza would arrive faster than an ambulace, in great britain.. 5% of the population is gay.. 1 on 4 women have had a homesexual experience.. etc.. After hearing the song, one question remains: Are all these “facts” actually true? Many of them depend on pretty sketchy survey evidence, but one set of facts given was open to easy scientific investigation, and that’s what we’ve done: we did a real experiment and even wrote some things in a notebook, so it must be True. The fact as stated was that a can of Diet Coke would float but a can of normal Coke would sink. Easy enough to check out. I brought home some samples: 1 can of Diet Coke, 1 can of Coke Classic, and one can of Mountain Dew as a control. Before getting anything wet, i decided to take weight measurements. Here were the results: Diet Coke

367.5 g

Classic Coke

382.5 g

Mountain Dew

392.6 g

I’m assuming that these 12 oz sodas are all similar volumes. accurate measuring of this was impossible at this time. The experiment was to simply put the can in a container of water to see if it floated. The temperature of both were room temperature, but i don’t think that barring things like heating either the water or the can that the difference in temperature i’d be likely to us would make an insignificant difference in tbe results. I did the diet coke first, which floated with a bit of the can above water. The regular can of coke would not stay on the bottom. WHen in a shallow container, one end stays on the bottom. Subsequent experiments showed that the can wants to stabilize in an straight up-down orientation. The Mountain Dew sat at the bottom of the bowl and did not attempt to float at all. When the water was deep enough, the Classic Coke floated just at the level of the water with nothing above the water’s surface. Its density is very close to that of water, in other words. I didn’t have a chance to weigh or measure a beer can but since alcohol is lighter than water, i expect that it would float about as much as the artificially sweetened Diet Coke. It was suggested that the degree of flotation could be changed by shaking the can up, but this didnt make any change, and it makes sense that it wouldn’t: While shaking the can will free more gas from the soda, toe total volume is fixed and the liquid isn’t going to compress, so while there is more gas freed from the soda all it changes is the pressure of the gas and the total volume of gas vs the total volume of liquid will stay the same as long as the can doesn’t open. So: Coke floats whether it’s diet or not, and mountain dew sinks.