What is Hair: Definition and 133 Discussions

Hair is a protein filament that grows from follicles found in the dermis. Hair is one of the defining characteristics of mammals.
The human body, apart from areas of glabrous skin, is covered in follicles which produce thick terminal and fine vellus hair. Most common interest in hair is focused on hair growth, hair types, and hair care, but hair is also an important biomaterial primarily composed of protein, notably alpha-keratin.
Attitudes towards different forms of hair, such as hairstyles and hair removal, vary widely across different cultures and historical periods, but it is often used to indicate a person's personal beliefs or social position, such as their age, sex, or religion.

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  1. P

    Does Cut Hair Contain Nuclear DNA?

    Is it true that hair that is cut from your head (not pulled), does not contain any nuclear dna ? My understanding of hair structure is that it is a matrix with at least some dead cells present in various layers. Eg the outside cuticle is made of flattened cells . Feughelman, Max Mechanical...
  2. O

    Power rating of a heater in the same outlet as a hair dryer

    Homework Statement A heater is plugged into the same 120-V AC outlet as an 800-W hair dryer. If the total rms current drawn is 16.7A, then calculate the power rating of the heater. Homework Equations Pav=\frac{1}{2}I2peakR The Attempt at a Solution Irms=Ipeak/\sqrt{2} So...
  3. M

    How Did Mighty Atom's Hair Defy Physics?

    'It is a fact that this modern Samson's hair was so strong it could not be pulled out. One of the most astounding feats of strength ever seen was headlined by the Buffalo (New York) Evening Times on September 29th, 1928: "Mighty Atom -- Super Strong Man Pits Brawn Against Plane, Wins." At the...
  4. C

    The No Hair Theorem and the Gravitational Field of Black Holes

    How come the gravitational field produced by black hole is independent of mass distribution within the black hole? Suppose, for example, you have a specific massive object close to the surface of black hole , then wouldn't the gravitational field on that side of black hole somehow be different...
  5. O

    What charges on my hair after comb?

    After I comb my hair, does it supposed that my hair is positively charged and the wood comb is negatively charged? since the electrons went from your hair to the wood comb. Thanks in advance for any suggestions
  6. alexmahone

    MHB Why do most people have black hair?

    What kind of evolutionary advantage does black hair confer? I would have expected most people (young as well as old) to have white hair because it reflects heat and therefore keeps heads cool.
  7. micromass

    Music The Most Annoying Music To Rip Your Hair Out To

    Not all threads need to be constructive. So tell me your worst, most annoying music out there. What tune makes you rip your hair out??
  8. P

    Mastering Hair Physics: Tips & Tricks for Smoothly Simulating Hair Movement

    Hi, I'd like to ask some help and suggestions about simulating hair physics (so basically pulling hair vertices around, and smoothly disposing the adjacent ones). Please take a look at the embedded video (which shows an application tha can do it): the hair displayed there is made of 15...
  9. K

    Pulling my hair out over this one

    1. An object with a mass of 56 g displaces 352.8 ml of water when it is completely immersed. What is the buoyant force on the mass? Notes: * Report your answer in Newtons and use N as the unit. * Report your answer to one decimal place. * Acceleration due to gravity = 9.8...
  10. R

    Why someone cannot raise him/herself up by holding the hair?

    Can someone please answer this question in terms of the forces acting?
  11. P

    Physics career and guy with long hair?

    Silly question I know but can you have a career as a physicist and be a guy with longer hair?
  12. D

    Do other mammals get gray hair?

    Do other mammals besides humans get gray hair as they age? Or is it a uniquely human thing for hair to turn gray?
  13. Pythagorean

    Medical Can Water-Only Showers Really Treat Skin and Hair Issues?

    I had issues with dandruff for a long time. Once my second kid was born, I went two weeks without a shower. My dandruff basically went away. Since then I've been showering with water only. My hair has become way healthier and my skin is all a consistent color and doesn't get scraped and...
  14. R

    Searching for chemical to apply to hair

    Hi, We sell hair products; both synthetic and human hair. Sometimes the customer will cut the hair and then say the hair was too short and request a refund, discount or exchange. We are searching for a safe chemical that we can apply to the ends of the hair so we know if the customer has cut...
  15. T

    Hair brained, universal mapping theory (nonsense ?)

    Firstly, Hi everyone :) Secondly, please forgive my virtualy non existent knowledge of any theories that this relates to. I'm not a Dr,MD, or even a graduate. I'm not even studying anything anywhere. I have a few 'problems' (chronic anxiety, depression, yada yada yada) not looking for sympathy...
  16. D

    Does radiation from phones/PC's increase hair loss?

    Does radiation from electrical devices such as computers, phones, WiFi etc.. have an effect on hair loss? Can't really find a lot of articles on the net about it.
  17. D

    Why does hair on a human head grow indefinitely?

    Given that we humans are descended from the great ape, as well as are gorillas and chimpanzees and bonobos, why do we have hair that grows indefinitely, while they do not? I've read something about a sexual selection aspect to evolution, surmising that hair is a means to finding a mate, like...
  18. J

    Plucking a white hair would result in more white hairs

    I have heard people saying that if you pluck a white hair then it would only result into more white hairs coming out. Is there any truth in it? Please let me know. Thanks.
  19. O

    Why does thin hair create a horizontal diffraction pattern?

    So I understand that thin hair or wire can make a diffraction pattern, but why would the diffraction pattern be horizontal when the hair is vertical?
  20. J

    Non-linear Differential Equation - Pulling my Hair

    Non-linear Differential Equation - Pulling my Hair ! Hi, What seems like a simple problem could be going abit better. Any ideas would be sincerely appreciated. (y'')^2 -xy'' + y' = 0 The squared term is causing me grief ! If I set say v = y' , that still leaves me with the squared term...
  21. R

    Can only one parent with blonde hair produce blonde offspring?

    I have always heard that the recessive gene for blonde hair needs to be in both parents in order for it to pass onto the children. Yet, I've read of many cases where only one of the parents carries the gene for blonde hair and somehow the children end up being blonde.
  22. J

    Medical Is leaving the shampoo in your hair for a long time dangerous?

    Is leaving the shampoo in your hair for a long time dangerous? Wouldn't that give the scalp more time to absorb the active chemicals in the shampoo? And is it really impostant to rinse off your shampooed head thoroughly to wash away all the shampoo? Is using a separate conditioner better than...
  23. J

    Name of the tissue of cells which is responsible for production of hair

    I'm not a biology students, so please use the simple language. The group of cells working in coordination for the same end is called a tissue. The combination of different tissues working in harmony together is called an organ. Different organs functioning according to some defined rules...
  24. P

    Maximize Weight Lifted with Hair Dryer Machine | Homework Help

    Homework Statement Basically, using only a hair dryer as the source of energy, students need to create a machine that will lift a maximum amount of weight. Students get graded according to who can lift the heaviest weight. The record seems to be around 40kg...Homework Equations Can anyone...
  25. Loren Booda

    Exploring the Limitations of the No Hair Theorem in Black Hole Dynamics

    "No Hair" theorem? Why are "No Hair" variables limited to angular momentum (in particular), mass and charge - which together determine the external spacetime of a black hole?
  26. cepheid

    Medical Efficacy of Laser Hair Treatment

    I apologize if threads on this topic have been posted already. I don't frequent the medical sciences forum. My question is whether there are any rigorous scientific results published in peer-reviewed journals on the efficacy of what seems have been dubbed "low level laser therapy" (LLLT) as a...
  27. J

    Infected from Dog Hair - Have You Experienced This?

    I just cleaned out the vacuum cleaner which was filled with dog hair. It reeked of dog when I opened it up. A few seconds later I felt itchy in several places..I figured it was just fine dust particles that were irritating my skin. Then I went into the bathroom and saw that my skin had...
  28. J

    Wax that doesn't stick to hair

    Hello, I'm looking to improve on a surfboard wax recipe. My goal is to still provide the same stickiness needed to stay on a board yet not stick to hair. The current formula I use is very simple. 3 parts beeswax 1 part coconut oil Obviously the beeswax mixture sticks to everything...
  29. G

    Radiant Energy Absorbed by Person's Head with Hair

    Homework Statement A person is standing outdoors in the shade where the temperature is 28 degrees C. What is the radiant energy absorbed per second by his head when it is covered with hair? The surface area of the hair (assumed to be flat), is 160 cm^2 and its emissivity is 0.85. Homework...
  30. S

    About the epidermial cell of the root hair.

    Anyone one here, knows any link where there will be a diagram of the epidermal cell of the root hair cell? If not, could you please explain to me everything about the epidermal cell of the root hair.
  31. Matterwave

    Can quantum entanglement violate the no hair theorem?

    Yea, so I was thinking...the no hair theorem says that you can only know 3 things about the matter inside black holes - mass, angular momentum, and charge right? But what if I create a pair of entangled particles, and throw one of them into a black hole...will I then know information about that...
  32. K

    Can Black Holes Have Hair in Higher Dimensions?

    Does anybody roughly now the basics of why you can have hairy black holes in more than 4 D? Thanks :)
  33. V

    Male Hair Help: Choosing the Right Cut for Long Hair

    I have ridiculously long hair (past my nipples), and I want something short. I really have no idea what to ask for when I go to the barber tomorrow. Any ideas? I can post a picture if that would help.
  34. S

    Optics-Diffraction of Thin Hair

    Optics--Diffraction of Thin Hair Homework Statement A human hair is illuminated with a laser and it produces a diffraction pattern on a screen 1.09 m away. If the distance from the center to the first minimum is 4.8 mm and the wavelength of the laser is 748 nm, what is the thickness of...
  35. C

    Procerin - agents that engender hair growth

    im browsing through products that potentially reverse the cessation of hair growth on one's head. that which I am observing is as follows: procerin ingredients: approximated daily value Saw Palmetto Berries 1500mg ** Zinc...
  36. S

    Ionic Hair Dryers: Rune's Investigation

    When trying to find a good hair dryer the other day, I stumbled across something called ionic hairdryers. They seem to be very common; most brands that produce hair dryers seem to have dryers that possesses this mystic quality. I've been trying to find out what this 'ionic' really means, but...
  37. D

    Medical What should I do for my greasy hair?

    Hey, My hair gets greasy/oily every day. I have tried many kinds of shampoos, but they did not work. Some people say, shampoos makes it even worse, some say use this one, that one...What's wrong with my scalp/hair that produces this much grease? What's the remedy? Thanks. I am male by the...
  38. B

    Grey Hair Reversal: Are There Any Drugs Without Side Effects?

    Hello all, So I realize the topic of how to reverse the greying process has been beaten to death with no clear solutions yet. However, my question is whether any drugs have been shown to cause the greying process in hairs, with no stem cell side effects. Anyone?
  39. D

    Can stress really turn hair white?

    Is it really true that stress can turn hair white? I know of people (including myself) who are in their 20s, and yet already have strands of white hair, in some cases quite numerous. And if so, then approximately how does that occur and how long does it take to occur? Also, does this apply...
  40. E

    Paying someone to cut your hair

    I think it is an abomination that a barbershop can stay in business. Every human being that owns a scissors and has at least one hand is capable of cutting his or her own hair perfectly fine. If you begin cutting your own hair when you are a child then my guess is that you will save...
  41. A

    How can I solve my hair problems?

    Hi friends I am having heavy hair fallings, i used too many haircare products conditioners and shampoos,but no use, Now my head look bald head, what to do.. I think using hair extensions better.. Can anyone suggest me...!
  42. A

    Calculating Energy Usage of a Hair Dryer

    [SOLVED] Power problem! Homework Statement (a) How many joules of electrical energy are used by a 1650-W hair dryer in 10 min? (b) If the dryer is operated a total of 4.5 h during one month, how much will this contribute to the electrical bill if the billing rate is 12 cents/kWh...
  43. J

    Medical Why Do Some People Have No Hair on Legs and Arms? Genetics vs. Other Factors

    Except the genetic factors, why do some people not have a single hair on legs or arms while some are full all over the body ? I rarely see North American men without facial hair. On the ads I have read, there are even cream or medicine that helps hair growing. that's really funny. Is it good...
  44. X

    Ayren purchased a 1000W (120V) hair dryer in the USA,

    Ayren purchased a 1000W (120V) hair dryer in the USA, and she took it to Europe where the standard voltage is 220V. Assuming that the hair dryer can operate safely at the higher voltage, can you actually use it if the outlet is rated for 15A, or will it draw too much current (How much current)...
  45. M

    Solving Punnet Squares for Dark Hair & Brown Eyes

    [SOLVED] Punnet Squares The allele for dark hair D is dominant over that of red hair d, and the allele for brown eyes B is dominant over that of blue eyes b. A women is red-haired and has blue eyes. Her husband is dark-haired and has brown eyes. a) What are the possible genotypes for the...
  46. W

    Turning Gray at 23: Reflecting on Genetics & Life

    Normally it wouldn't be a big deal for an older person, but it is for me as I'm only 23. My hair is brown with sometimes blond sprouts here and there. But lately when I took a good look in the mirror I see a light grayish shade creeping over my hair. Normally I wouldn't worry, but I have to...
  47. H

    Hair color why the difference?

    Can someone explain to me why there are difference in humans hair color? Why black and blond and brown and red only? Why not green?
  48. A

    L'Hopital's Rule - I'm loosing my hair

    L'Hopital's Rule - I'm loosing my hair! Ok, I have the following: Lim x->0 sqrt(4-x^2) -2 /x After I change the equation to remove the radicle, I get: Lim x->0 ((4-x^2)^1/2 - 2)/x but when I apply the rule the, I'm loosing it I thought I should get: 1/2 ((4-x^2)^-1/2 times...
  49. T

    Higher resistance of hair dryer

    A hair dryer has two settings: 840 W and 1320 W. (a) At which setting do you expect the resistance to be higher? 840 W correct After making a guess, determine the resistance at each setting. (b) 840 W setting (c) 1320 W setting Homework Equations I am not exactly sure what...
  50. L

    Vandergraph generators and hair

    1. WHy does hair stand up when touching a vandergraph generator ,i know that negative charges repel other negative charges 3. is it the fact the hairs are negatively charged so repel each other or is it the electrons releasing into the air
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