Densities of the Planets

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Densities

Unfortunately you can't directly measure the densities of the planets, but if you would like to try your hand at a more challenging activity, click here: Finding the Densities of the Planets. However, you may find the following activity enLITEning!

All you need are two unopened soda cans, one diet and the other regular. They should be the same brand and the same size, usually 12 fluid ounces. Fill a sink or a bucket with water and place both cans in it. Having done that, can you tell which can is the "LITE" soda, even without looking at the label?

The two cans differ in density. The regular cola usually is more dense than water, so it sinks. The "LITE" soda usually really is light, or at least it has a lower density, so it floats. Why?

The regular soda has a large amount of sugar or corn syrup dissolved in it. (Regular COKE^tm used to have 17 spoonsful of sugar before they changed the formula to use corn syrup instead.) The molecules of sugar or corn syrup mix in among the molecules of water and other flavorings, without changing the volume, and make the soda more dense - -thus it sinks. The LITE soda uses an artificial sweetener, usually Aspartame, which is much sweeter than sugar and takes much less to sweeten the soda, making the soda less dense -- thus it floats.

Similarly, you can dissolve a cup or more of sugar into a glass of water without significantly raising the level of the water. The sugar molecules pack themselves down in the empty spaces between the water molecules, adding mass without adding volume, and making the mixture more dense. This is the same reason the Earth is more dense than Jupiter, although Jupiter is much larger and has much more mass overall. For a given volume, the Earth has much more mass than the same given volume of Jupiter.

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