How many hairs are on your head?

[Faiza]

Fermi Numbers!??

I'm trying to solve this problem and explain all my steps in my reasoning.

**HOW MANY HAIRS ARE ON YOUR HEAD?**

If anyone can help me figure this out, reply
thanking u in advance
faiza

 

[Faiza]

No Replies :( :'(

 

[Faiza]

:"( ......

 

[Claude Bile]

No of hairs on head is equal to;

No of hairs per unit area x Surface area of head with hair.

You need to get a value for both of these quantities, either through measurement or estimation (or both).

Claude.

 

[Faiza]

this is hard lol

 

[Gokul43201]

Using the average diameter of a hair (about 50 microns, or pluck a few hairs and measure them) you can determine a rough upper limit on the number of hairs. The actual number depends on the packing density, which I think, is not likely less than 10% coverage. So that gives you an approximate lower bound. Pick the mean to get an order of magnitude estimate.