Specific tensile stress is defined as the tensile strength of a material divided by its density.

• A. The elastic modulus divided by density.
• B. The yield stress divided by density.
• C. The tensile strength divided by density.
• D. The energy absorbed before fracture.

Answer: (C)

The idea being tested is specific strength, the material’s strength per unit weight. Specific tensile stress is defined as tensile strength divided by density, because tensile strength measures how much load a material can carry in tension, while density tells how heavy it is per volume. Dividing strength by density gives a measure of how much strength you get for each unit of weight, which is crucial when weight matters (like in aerospace or automotive design). In units, tensile strength is in Pascals and density in kg/m^3, so dividing gives a quantity with units of m^2/s^2, reflecting strength per weight.

This is the best definition because it directly compares how strong a material is relative to how heavy it is. The other metrics are related but describe different properties: elastic modulus divided by density is specific stiffness, yield stress divided by density is specific yield strength, and energy absorbed before fracture measures toughness, not a strength-to-weight ratio.