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.