Which material is described as having the highest strength-to-weight ratio?

• A. Carbon Fiber
• B. Steel
• C. Aluminum
• D. Wood

Answer: (A)

Strength-to-weight ratio, or specific strength, measures how strong a material is for each unit of weight. The higher this value, the more load you can carry for a given weight. Carbon fiber shines here because it combines very high tensile strength with a very low density. Its density is around 1.6–1.9 g/cm³, while steels are about 7.8 g/cm³ and common aluminum around 2.7 g/cm³, yet carbon fiber composites can achieve very large strengths. The result is a much higher strength-to-weight ratio than metals or wood, which is why carbon fiber is favored when lightweight, strong materials are needed.