Expert: Florence M Rollwagen - 1/24/2009

Question
1. Can we remove entire hair on our scalp by pulling it instead using scissors?
2. Can we remove all the hair on our scalp by strain of 500 pound or 1 ton?

I heard that single hair can cope with strain of 3.5 ounces, really??

Also can billions of hair break a bone if we wrap the hair around the bone, place heavy thing on the middle of the bone, and then pull the hair to break the bone? (I think this question is a bit strange because my friend said a very great mass of hair can break a bone that make me feel very odd, is it true???)

Answer
Hi Bobo:  Thanks for your question (s).   

Q1:  Yes, there have been industrial accidents in which hair got caught in machinery.  Instead of breaking, the scalp was pulled off.

Q2:  A full head of hair can support about 15,000 lbs.  Remember, a ton is 2,000 lbs. (http://en.wikipedia.org/wiki/Hair_hang)

Q3:   A single hair can support about 100 grams (3.5 oz)
(http://en.wikipedia.org/wiki/Hair_hang)

Q4:  Obviously, it would depend on which bones we were talking about.  

Hair is actually quite strong, with a tensile strength of about 1.6*10-9N/m2.  N= Newtons, a unit of strength.  M2 = square meter.  (http://www.keratin.com/aa/aa016.shtml)

The breaking strength of a rat tibia is about 160 N/m2
(http://www.springerlink.com/content/q6027381v0341l72/)

That’s 0.0000000016N/m2

So it would take about 8 hairs to bread a rat tibia (shinbone).

I gave you the links in case you want to check out more information.

Hope this helps!

FM Rollwagen, PhD