Which property is defined as tensile strength divided by density?

• A. Specific tensile modulus
• B. Specific tensile stress
• C. Fatigue life
• D. Hardness

Answer: (B)

Specific strength is the key idea here: it’s tensile strength per unit density. Tensile strength is how much load a material can carry in tension before it fails; when you divide that by density, you’re measuring how much strength you get for each unit of weight. This ratio is often called specific tensile stress, and it’s especially important for designs where weight matters (airframes, spacecraft, etc.). The units come out as m^2/s^2, reflecting strength relative to mass, and materials with high specific strength—like carbon fiber composites—give you more strength for every kilogram compared with heavier materials. Others properties, such as hardness or fatigue life, don’t involve density in this way, and specific modulus would use stiffness (modulus) instead of tensile strength.