Density
The mass of individual atoms and how closely they are packed
together can be "felt" on an every day level - it is called the density of the material.
Density is
important in every day life, for example if this book was made of solid gold it would have a
mass of 5.5 kg! Clearly a problem to use! The same applies to power cables, they are made
of aluminium as it is lighter than steel and so the pylons are strong enough to hold them
up.
The table below shows the density of some common materials.
In an extreme case we could
work out the density of a proton! It has a mass of roughly 1.66 x 10
-27 kg and a
"diameter" of 10
-15 m. This gives it a "volume" of 4.2 x 10
-45 m
-
3 and a density of just under 4 x 10
17 kgm
-3, whatever that may
mean!
