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Is a strand of hair stronger than a strand of steel the same size?
Question Date: 2007-12-14
Answer 1:

Yes and no; it depends on what kind of strength you mean.

There are two kinds of mechanical strength: compressional strength and tensile strength. Tensile strength is how strong the material is when being stretched. For something like a cable to hang something from, you want high tensile strength. Compressional strength is how well the substance resists being squished. For something like an arch, you want compressional strength.

Hair is made out of protein. Proteins, by and large, are great at tension and awful at compression. For tensile strength, yes, hair is stronger than steel.

For compression, well, feathers are made out of the same protein, and you know how hard pillows are!

Answer 2:

Here are typical ultimate strengths of different materials when pulled.These can all vary depending on purity:

Nylon thread: 75 MPa
Human hairs: 200 MPa
Ordinary structural steel: 400 MPa
Silk: 500 MPa
Spider web (dragline): 1200 MPa
Piano wire steel: 2300 MPa
Carbon Nanotube: 62000 MPa

So it looks like human hair is stronger than nylon but weaker than almost any steel. Piano wire is much stronger, and spider silk is in between. Carbon Nanotube could be the strongest thing, although we currently don't know how to make them longer than about 1 mm.

They're also super stretchy before they break, which could be a good thing or a bad thing, depending on what you want to use it for.

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