We were reviewing fluid forces in Calculus II today. I decided to give an example using items from the room. The first fluid I found was my Diet Mnt Dew (the "Mountain" was replaced by "Mnt" a while ago). The mass density is 901 kilograms per cubic meter. The weight density is 8830 Newtons per cubic meter.
One of the students asked if the density would change as the carbonation is released. Our chemistry professor at the college said that the density would change, but not enough to be noticeable.