9.5 pcf, tensile strength 1910 psi (that’s pretty strong stuff, a 1" square piece of balsa wood holding one ton of weight) Standard Grade 60 structural steel is about 500 pcf and has a tensile strength of about 60,000psi (thus the name). Tensile strength/density ratios are thus: 1910/9.5 = 201 60000/500 = 120. More @Wikipedia
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