Which material has the highest strength-to-weight ratio?

• A. Kevlar
• B. Aluminum
• C. Carbon fiber
• D. Fiberglass

Answer: (C)

Strength-to-weight ratio, or specific strength, measures how much load a material can carry for its weight. A high ratio means you get more strength without adding much heft. Carbon fiber stands out because it combines very high tensile strength with a low density, so per kilogram you gain a lot of strength while keeping the mass down. Kevlar is light and strong, but carbon fiber typically offers a higher strength per weight. Aluminum is lighter than many metals but doesn’t reach the same strength per weight as carbon fiber, and fiberglass is heavier and not as strong per weight as carbon fiber. That combination of strong and light makes carbon fiber the best choice for maximizing strength while minimizing weight.