how many hairs are there in a nornal man head ?

Answer 1

Blonde= 140 000 hairs

Red= 90 000 hairs

Brown= 100 000

Answer 2

How many hairs are on a head?

Solution: Where do you begin to answer such a question? Whose head is being discussed? Well, to begin with, since every head is different (from the thickest head of hair to the totally bald) it must be assumed that we're going to take some average person's hair. The method we'll use is quite straightforward. Namely, we will estimate the area of the scalp and then multiply by the estimated number of hairs in a small unit of area.

First, to get the area of the scalp we use a geometric approximation which will be our model. We do this because the actual determination of that area would be difficult to make for any single head and because an exact result (say to 2 figure accuracy) would be representative of only that one head. Since heads vary in size even among adults (probably by 10% to 20%) the model will do as well for the approximation we're trying to obtain. Now the model is a hemisphere of the same diameter as a typical adult head. That diameter is about 10 inches or 25 centimeters. Check your own head by looking in a mirror with a ruler across your face.

The surface area of a hemisphere of radius r is half that of a sphere,

Area of hemisphere = 1/2 area of sphere = 1/2 x 4pr2 = 2pr2.

With the radius, r = 1/2 diameter = 5 in and p @ 3 , we get

Area of "scalp" = 2x3x(5in)2 = 6x25 in2 = 150 in2.

Note that p @ 3 is a close enough approximation to 3.141596... for our purposes; we're aiming for "order of magnitude" accuracy. That means the nearest power of ten, as you'll see.

Next we need some estimate of how many hairs are in a typical patch or unit of area. By counting the number of hairs roughly along a line of 1 inch, somewhere in the middle of your or your friend's scalp, you will get something like 15 to 40. Then squaring that, which assumes the hair is arranged somewhat like a checkerboard or grid, gives 225 to 1600 per square inch.

Combining these two factors we have the number of hairs equals

150 in2 x (200 or 1600)in-2 = 30,000 or 240,000 hairs.

Note that I've rounded off the 225 to 200 which is justified by the large uncertainty in our estimates. The result is somewhere between 0.3 X 105 and 2.4 X 105 (using "scientific notation" for the powers of ten involved). We can say that the relevant order of magnitude is 105.

Then that rough approximation to the answer gives the interesting result that among 10 people there are about one million hairs on their collective heads (excluding beards). So, if you now are told that your chance of winning something (like a lottery for example) is one in a million, you can visualize that. It is the chance of randomly picking one single secretly marked hair in one try from the heads of 10 people. Not very likely!

Answer 3

I think something like 200,000 strands, but I could be off by a zero. Of course, "2,000,000" sounds like too much, right? It must be 200,000. Oh, wait, I see the post above me halves the figure I put up. Anyway I've also heard that we shed about 200 hairs a day on average.

Answer 4

It varies widely!!! Why don't you find out yourself. Measure off 1 square cm on someones head, count the hairs in that small space then multiply by the surface area of the scalp.

Answer 5

Hair density depends upon race and hair color. In Caucasians, people with blonde hair have an average of 140,000 hairs; brunettes or dark-haired people will average 110,000 hairs; and red-haired individuals will have the least density with an average of 90,000 hairs.

Answer 6

I was gradually lossing hair since '02. Now I started to fight it when my hair to start getting thinner. So, all I can say is for me, not many hair are there.

Answer 7

and i suppose you meant normal rather than nornal.....and that ..totally depends on the...gene or that person...

Answer 8

oh its easy to find out...its as same as the number of stars in the sky

Answer 9

aproximately 1 million..

Answer 10

4 million.

if u don`t believe it then count urself.