1. Not finding help here? Sign up for a free 30min tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Fermi Numbers?

  1. Sep 28, 2004 #1
    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
     
  2. jcsd
  3. Sep 28, 2004 #2
    No Replies :( :'(
     
  4. Sep 28, 2004 #3
    :"( ...............................
     
  5. Sep 28, 2004 #4

    Claude Bile

    User Avatar
    Science Advisor

    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.
     
  6. Oct 1, 2004 #5
    this is hard lol
     
  7. Oct 1, 2004 #6

    Gokul43201

    User Avatar
    Staff Emeritus
    Science Advisor
    Gold Member

    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.
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?



Similar Discussions: Fermi Numbers?
Loading...