Not only eggs but people float in saltwater like corks! But why does salt help? And why things float?
According to the old story, Archimedes (287 B.C.- 212 B.C.)
figured it out while bathing and ran out into town without
his clothes crying "Eureka!"
Let's start with plain water. It is pretty obvious that water can
hold up water. This obvious fact is exactly how floating works: if
something is heavier than water of the same volume, it sinks, if it is
lighter than water of the same volume, it floats to the top. And what
happens if it weighs the same as water of the same volume? You can test
your guess with some water and two drops of different food colorings.
Now, back to salt water. If you weigh a cup of water, and then
weigh a cup of salty water, it turns out that a cup of salty water is
heavier. The more salt you dissolve, the heavier is the cup of salty
water. (Books say that salty water has 'HIGHER DENSITY'. Density is how
much a UNIT VOLUME weighs, such as cubic inch, or cubic mile, or a
Salty water can hold up salty water, that is it can hold up
heavier stuff than plain water can.
An egg weighs more than an imaginary egg made of plain water, but
it weighs less than an imaginary egg made of salty water. So salty
water can hold it up, and plain water cannot. That is how it works.
Because Dead Sea is much more salty than most world's oceans, and we are made mostly of water you can float in the
Dead Sea without even trying. Here
are pictures of people floating in Dead Sea reading a newspaper!
Next question to ponder- why ships made of iron float? At the
University of Illinois engineering students build concrete boats that
(republished on 07/31/06)