5

Homework #7

•Q4.
If a type G star like the sun expands to become a giant star with a
radius 20 times larger, by what factor will its density decrease?

–Density
is mass/volume.

–Volume
of a sphere is 4/3πr3.

–If
r increase by a factor of 20, volume increases by a factor of 20
cubed, or 8000. Mass remains the
same, so density decreases by 8000 times.