General Physics Problem

1. Feb 5, 2008

NosajW

A human hair is about 100 μm across. Estimate the number of hairs in a typical braid.
The average number of hairs on a person’s head = 100,000, and the answer is supposed to be 10,000. Can someone explain how you would get 10,000? Thanks in advance

2. Feb 5, 2008

John Creighto

Is this homework? It's not really classical physics. Anyway, I presume you estimate the radius of a ponytail, compute the area pi*r^2, then convert the area into units of hair diameters per m^2.

Now this wouldn't be the densest possible solution but I presume hair is not densely packed.

3. Feb 5, 2008

NosajW

Yeah it's homework and I am taking classical physics so I thought I'd post it here. This is the beginning of the course so we're doing units and basic stuff. This question is ridiculous, how big is the radius of a typical braid supposed to be anyway.

4. Feb 5, 2008

John Creighto

I don't know, try an inch and see what you get. BTW there is a sub forum here for homework problems. Remember, it said estimate. You don't need to get exactly the same answer. But if you want Google average human braid diameter and see if you can find anything.