For a star of constant density, calculate the fraction of the total mass inside a core of radius R/4, if the radius of the star is R.
I have no idea.
Thanks for any help.
Sorry, but I have no idea what "calculate the fraction of the radius R/4" means. Since you mention density, do you mean calculate the mass out to radius R/4 or the fraction of the total mass that is? Do you know the formula for volume of a cube? Mass is just density times volume.