rho is density and g is acceleration of gravity. If you are forming a ratio of mass per unit length of the same materials, everything cancels except the volumes.
The volume per unit length is simply (pi * d^2)/4 which is the cross sectional area of a cylinder. So the ratios of masses per unit length is the ratio of diameters squared.
I attempted to get you to figure the formula out because we are not permitted to merely hand out formulas and solutions. Anyone can plug into a formula and get the answer. Figuring out how to derive the formula separates the better students from the pack.
We Value Quality
• Topics based on mainstream science
• Proper English grammar and spelling We Value Civility
• Positive and compassionate attitudes
• Patience while debating We Value Productivity
• Disciplined to remain on-topic
• Recognition of own weaknesses
• Solo and co-op problem solving