DharmanKothari wrote:Actually what you are trying to find is called Ultimate Tensile Strength or the Ultimate Strength (the point at which if the material is ductile, it starts to "neck"i.e.start thinning out before breaking, or in case of brittle material, completely breaks).
The Elastic Limit is actually the point after which Hooke's Law (which says that the deformation will increase proportionally with increase in force) no longer applies and your material has permanent deformation (even if you remove the force).
Now that we have the technicalities out of the way, I can not understand why you would want to do anything other than pulling to find the ultimate strength, since "pulling" or tensile testing is what even professionals in the materials industry do to find the ultimate strength of a material.
What I would suggest you do is that you find a small pan, tie one end of the uncolored hair to it and tie the other end to a vertically standing hook and increase the weight in the pan incrementally until the hair breaks. Repeat for the colored hair and repeat multiple times to get a good average. You can find the force by using F=mass*gravity and if you are looking for the ultimate stress then it would be Stress=Force/Area. I leave it up-to you to find the cross-sectional area of a human hair. And don't forget to weigh the pan too.
Having said that, it is very important that when you are performing these tests on those hairs to make sure that they have the same cross-sectional area since Ultimate Strength depends a great deal on the cross sectional area of your material. I know it will be next to impossible but try your best to have those hairs of similar dimensions.
If you need some more info on these things, I would suggest you to Google Tensile stress and you can find a lot of information about it.
Hope this helps!
alondra011 wrote:...If Using the formula F=Mass*Gravity is the most effective way I know that I will be finding the force after the mass (the objects/weights in the pan + the weight of the pan) times the Gravity. If gravity is 9.81 meter per second. How am I supposed to find the seconds? ...
John Dreher wrote:According to Wikipedia (18 Nov 2012)
"The diameter of human hair varies from 17 to 180 micrometers (0.00067 to 0.0071 in)."
You could measure the diameter using diffraction of light from a laser, as described here:
You could make a bundle of 100 hairs (tedious) and measure the diameter of the bundle (about half a mm maybe?). From that the area of each hair is 0.01 of the area of the bundle ( pi*(diam/2)^2 ).
You might be able to use a micrometer on a hair.
You could look at the hair and a reticle (a kind of ruler for use under a microscope) with a microscope.
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