The ratio of the tensile (or compressive) strength to the density of a material is a measure of how strong the material is "pound for pound."
(a) Compare tendon (tensile strength 80.0 MPa, density 1100 kg / m3) with steel (tensile strength 0.50 GPa, density 7700 kg/m 3): which is stronger "pound for pound" under tension?
(b) Compare bone (compressive strength 160 MPa, density 1600 kg / m3) with concrete (compressive strength 0.40 GPa, density 2700 kg / m3): which is stronger "pound for pound" under compression?