Estimate the number of hairs in a typical braid

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Homework Help Overview

The discussion revolves around estimating the number of hairs in a typical braid, with a focus on the dimensions of human hair and the average number of hairs on a person's head. Participants are trying to understand how to arrive at the estimate of 10,000 hairs in a braid.

Discussion Character

  • Exploratory, Assumption checking, Problem interpretation

Approaches and Questions Raised

  • Participants discuss estimating the radius of a braid and calculating the area to determine the number of hairs that could fit. Questions arise about the typical size of a braid and the density of hair packing.

Discussion Status

Some participants have provided initial thoughts on how to approach the problem, including suggestions for estimating dimensions. There is acknowledgment of the question's nature as homework, and participants are exploring different interpretations of the problem without reaching a consensus.

Contextual Notes

Participants note that the question may not fit traditional physics problems and express uncertainty about the expected size of a typical braid. There is mention of homework guidelines that emphasize estimation rather than exact answers.

NosajW
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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
 
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NosajW said:
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

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.
 
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.
 
NosajW said:
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.

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.
 

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