What is Head: Definition and 411 Discussions

A head is the part of an organism which usually includes the ears, brain, forehead, cheeks, chin, eyes, nose, and mouth, each of which aid in various sensory functions such as sight, hearing, smell, and taste, respectively. Some very simple animals may not have a head, but many bilaterally symmetric forms do, regardless of size.
Heads develop in animals by an evolutionary trend known as cephalization. In bilaterally symmetrical animals, nervous tissues concentrate at the anterior region, forming structures responsible for information processing. Through biological evolution, sense organs and feeding structures also concentrate into the anterior region; these collectively form the head.

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  1. M

    Trying to get my head around tangent bundles

    Hello, Say you have a function f on the domain R^n, and an integral transform P which integrates f over all possible straight lines in R^n. I am lead to believe that the range of this is R^(2n), or a tangent bundle, which I am having MASSIVE problems visualising! Am I right in saying the...
  2. B

    Momentum Head on Collision Cart Problem

    Homework Statement Two remote control cars with masses of 1.11 kilograms and 1.81 kilograms travel toward each other at speeds of 8.75 meters per second and 3.39 meters per second, respectively. The cars collide head-on, and the less massive car recoils with a speed of 2.99 meters per second...
  3. R

    Circular Drum Head Modes: Understanding Why They Don't Always Follow the Rules

    The modes of a circular drum head are described by Bessel functions and sines and cosines, but without getting into all that, one can making the following statement: the nodes are circles concentric with the center of the drum, and are also evenly spaced lines that run through the center of the...
  4. U

    Magnetize a steel wire by rubbing against your head. (BS or ~BS)

    Who can help me call BS on the physics of something I just watched on TV. Ok let me clarify that statement, of course 90% + of what's on TV is BS but this particular show is a documentary style that so far seemed reasonably well grounded in fact (though at times somewhat contrived). The show...
  5. H

    Solving Head Start Questions for Cars A & B Races

    Homework Statement Cars A and B are racing each other along the same straight road in the following manner: Car A has a head start and is a distance D_A beyond the starting line at t = 0. The starting line is at x=0. Car A travels at a constant speed v_A. Car B starts at the starting line but...
  6. P

    Pumping Warm Crude Oil: Calculating NPSA & Velocity Head

    At an oil refinery, a mobile centrifugal pump is used to pump warm crude oil from a storage tank. Liquid level in tank at elevation of 3 metres above pump. Suction side of pump is fed with a flexible hose that is 10 metres long. Crude oil density: 846 kg/m3 Crude flow 4000 kg/h Internal...
  7. B

    Just when I started to get things straught in my head.

    http://www.fourmilab.ch/cship/timedial.html Gives a formula for time dilation which is repeated in many other soucres. In this version t'/to increases with v. Its time dilation time is meant to slow? http://www.phys.unsw.edu.au/einsteinlight/jw/module4_time_dilation.htm A useful set of...
  8. Math Is Hard

    Microsoft Photoshop head switch

    ruh roh http://www.huffingtonpost.com/2009/08/26/microsofts-ad-in-poland-p_n_269366.html I couldn't resist making an animation from the 2 images. Now if I could just make the heads morph...
  9. A

    What is the Impact of an Apple Falling on My Head?

    If a apple falls on my head, what is the physical value that makes my head hurt?
  10. C

    One dimensional motion problem, overcoming head start

    I know this problem has been posted before, but I think my answer is correct and I want to know why it was considered wrong! Homework Statement Cars A and B are racing each other along the same straight road in the following manner: Car A has a head start and is a distance Da beyond the...
  11. A

    Special Relativity 4-vector problem - Doing my head in

    Homework Statement OK - the problem is thus: In an inertial frame two observers (called a & b) travel along the positive x-axis with velocities Va and Vb. They encounter a photon traveling in the opposite x-direction. Without using the Lorentz transformations, show that the ratio of the...
  12. S

    Either I need my head examined or this is worng

    http://library.thinkquest.org/10796/ch1/ch1.htm I have some down time for the next 3 months and figured I might as well do something constructive and teach myself physics. I am doing so on thee above website, but question 2 on section 3 has me stumped. This section is about when and how...
  13. X

    Having a Big Head (physically)

    Hi guys. Right now I'm 14 years old. All my friends say I have a big head, and quite frankly I do (I'm referring to physical size not actual having a big ego). I'm really tall for my age too, I'm 6'3. I was wondering if it's natural for people to have a big head an grow out of it. When I was...
  14. 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...
  15. D

    Linear momentum head on collision

    Homework Statement Two cars, one a compact with mass 1200 kg and the other a large with mass 3000 kg, collide head on at 60 mi/hr. a. Which car has a greater magnitude or momentum change? Which car has a greater change in velocity? b. Which car's occupant's would you expect to sustain...
  16. J

    Can you see the back of your head

    if you stood on a mountain would you be able to look straight ahead with a powerful telescope and see the back of your head? or would you just look out into space?
  17. R

    Medical Neuroscience Q. - How long do new learned material stay in your head for?

    Man I hate forgetting. What I've done so far is log my study times to optimize my spacing. The logs are put on the first page of my binders. Let's say on Day 1. You learned a new concept, the class took 1 hour. You go home and do the 3 hours of practice homework. How long will it take on...
  18. I

    Finding Force and Angle for Mop Head Movement

    Homework Statement In Figure 6-62 a fastidious worker pushes directly along the handle of a mop with a force . The handle is at an angle θ = 40° with the vertical, and μs = 0.61 and μk = 0.48 are the coefficients of static and kinetic friction between the head of the mop and the floor. Ignore...
  19. M

    Head of fluids & Engine Efficieny.

    Homework Statement A pump delivers water at a rate of 60L/s with a head of 65m. It runs for 8 hours per day. The efficiency of the pump is 75%. The efficiency of the electric motor driving the pump is 80%. i) What is the value of the head in kPa ii) Calculate the input power kW that is...
  20. Ivan Seeking

    Medical Brazilian Man With Spear in Head: Done With Underwater Fishing

    http://www.google.com/hostednews/ap/media/ALeqM5he5maBJhjnx6v5XMKAQT9UcI_rjg http://www.google.com/hostednews/ap/article/ALeqM5h5d2mCkhRUjwl0pEAXfoSKpIc-TgD97A3AJO0
  21. R

    End effector with fish head kinematics

    End effector with "fish head" kinematics Hallo, I'm student and I have learned and read about end effector of robots. Could you recommend me some articles, www pages, pictures or videos about end effector with "fish head" kinematics? Do you know companies, which sell or development end...
  22. N

    Shower head for feeding water onto a solar thermal panel

    "shower head" for feeding water onto a solar thermal panel Homework Statement The question is homework to me, but I haven't actually seen formal physics classwork since college, 41 years ago. Please advise if this question is misplaced. I'm building a "shower head" to trickle or spray...
  23. BWV

    Trying to get my head around some basic exterior calculus concepts

    Trying to get my head around some basic exterior calculus concepts So #1 - 1-form or covector the grad is a covector / 1-form defined as something that combined with a vector takes it to a scalar, for example divergence is a scalar which is the dot-product of a function with its grad (e.g...
  24. M

    Simple equation causing a lot of head ache

    Hi there! I was trying to solve an equation but got very perplexed by the fact that a certain number x=0 is both a solution and no solution: Here´s the equation: (x-a)[(x-a)^2+y^2+z^2]^{-3/2}+(x+a)[(x+a)^2+y^2+z^2]^{-3/2}=0 assume y=z=0: Now, the equation becomes...
  25. R

    Force of Head Striking a Marble Floow

    Sorry, but my math is a bit rusty but -- Recently while using a wheel chair I fell from a lift banging my head on a marble floor. the lift was 6 feet off the ground, plus adding 4 feet while in a sitting position, the total fall was between 9 and 10 feet. Could someone help me calculate the...
  26. J

    Calculating Head Loss from Enlargement in Compressible Fluid

    how to calculate head loss due to sudden enlargement in case of compressible fluid? hiiiiii guys, am graduate student, i want to know @ head loss in case of compressible fluid due to sudden enlargement...pls help me ...as soon as possible...
  27. K

    Pumps: Head, Discharge & Lubrication Oil Recommendations

    Hi all, I want to know the details of the pumps such as Which of the pump has the highest head? Which one has the Highest Discharge? The one highly recommended for lubrication oils? What is the real physical meaning of head? The relation between Head and Discharge in physical...
  28. E

    Joystick control of stepper(s), noob in over head

    So I know I am getting in over my head here, which is why I haven't started anything. I have never done any advanced electronics work, but I know what resistors, capacitors, ICs, and the like are. I can't design a circuit aside from a switch and an LED, but I can build them. Ok, enough of that...
  29. P

    Question -Substiution ALWAYS imagining invisible brackets in your head?

    Im in 2nd year of math now...so I know algebra but I was reading this from this website: "Substitution Every time we replace a part of an expression with a value or another expression, we are using the technique of Substitution. And, every time a substitution is performed, parentheses...
  30. G

    Trying to wrap my head around dimensions

    As far as i know, a dimension is basically spatial parameters in which "stuff" can move. I think that what bugs me the most about physics is that we know the what but not always the why... obviously this is not anyone's fault especially because finding out why things are the way they are is much...
  31. B

    Question regarding the bias voltage applied to a tape recording head

    So in a tape recorder, the quantity of magnetic moment imparted to a unit area of magnetic tape is not a linear function of the applied magnetic flux; the transfer function looks kind of like a cumulative distribution function, if that makes sense. So if one just ran an audio signal directly...
  32. hagopbul

    Pondered her claim And shook his head

    but it is not mine but i like it The Innocence Fades There were two young children Who played every day Over time, they fell in love Until the girl had to go away He watched her go His heart was sad And he felt like Part of him had gone mad Over time he grew old And his...
  33. H

    Head First Physics - view book via Safari trial or Google

    "Head First Physics" - view book via Safari trial or Google O'Reilly Books have recently released Head First Physics, which is an algebra-based introduction to the mechanics and experimental topics in the AP Physics B and A Level Physics courses. The book works from the ground up, using...
  34. G

    If I Were Obama My Head Would Explode

    http://news.yahoo.com/nphotos/Democratic-presidential-candidate-Sen-Barack-Obama-Jean-Charles-de-Castelbajac/photo//081003/481/b9bd8c072fdd4d8da8a10d013c9fe226/;_ylt=Aq8nHiXTS2gphRnpQIRr24UDW7oF Needless to explain the French prefer Obama.
  35. I

    Understanding Head-On Collisions: Definition and Impact in Physics"

    will it be correct if i define head on collision something like this: When, in a particular reference frame, the direction of velocities of two bodies lies along the common normal, the collision can be called head on even if their Center of masses doesn't lie along their common normal.
  36. 有

    Calculate the probability that a head will show

    A kind of the trigonometry question... Let θ be an angle in standard position such that cotθ=-4/3 and sinθ<0. Determine the exact value of sec θ Determine the number of solutions for (asinx-b)(acosx-a)(bsinx+a)=0 where 0≦x＜2\pi, if 0＜a＜b. A fair coin is tossed 60 times...
  37. wolram

    A7 Twin Carb Head: A Precious Find!

    I have just swapped some parts for an A7 twin carb head, these heads are like gold dust as there are so few remaining and it is in perfect nick :!) So have you ever found gold dust?
  38. F

    Things that make me laugh my head off

    1. failed erudition 2. eggcorns 3. malapropisms
  39. B

    Innovative Water Wheel Design: 260W Power from 0.8m Head

    The inventor of a water wheel claims that his design is better than a conventional overshot or breast wheel at extracting energy from water flows at low heads. He states that the design shown can generate up to 260 W of power from a head of 0.8 m. average household energy use over a 24-hour...
  40. T

    Could someone help me get my head around this Taylor Series stuff

    Homework Statement The Taylor series for f(x) = ln(sec(x)) at a = 0 is sum_(n=0to infinity) c(sub n) (x)^n. Find the first few coefficients. The Attempt at a Solution I've been trying to figure out where to start by looking it up...I've seen instructions that each coefficient is...
  41. C

    Cylinder head pressure at expansion phase

    Does anyone know what the pressure is inside the cylinder of an internal cumbustion gasoline engine at the expansion phase? I've been doing some research and I've seen answers ranging from 200psi to 600psi. seems like a significant range, does anyone know where i can get somewhat more accurate...
  42. Math Is Hard

    NASA Crazy Rasberry ants head for NASA

    http://www.computerworld.com/action/article.do?command=viewArticleBasic&articleId=9086098
  43. C

    Medical Can head transplants be used to save lives?

    http://www.time.com/time/magazine/article/0,9171,891156,00.html" So, perhaps one can transplant a terminally ill patient's head into someone's neck for a while (just like in case of Demikhov's dog experiments). Then one waits until a suitable donor becomes available and transplants the head...
  44. wolram

    New Hygiene Head Orders Staff to Wash Bearings

    We have a new hygiene head and she has just ordered her staff to wash bearings. omg, i have told her bearings need grease and i thought she understood but no, i re greased them and hygiene washed them again, well i am Holiday from tonight so i will leave a note in the book (expect machine to...
  45. Z

    Franck-Hertz (my head) Experiment

    My questions are about the classic Franck-Hertz experiment where electrons are given energy by an accelerating voltage. These collide with mercury atoms, raising their internal energy. The electrons are then left with insufficient energy to overcome the retarding voltage of a collector plate...
  46. N

    Medical Blinking lights can hurt your head?

    I was wondering, I have heard that watching a blinking light can give you a head ack and a seizure. Why does that happen because our computer screens and tvs, are just blinking lights. They blink at about 60-80 times a second.
  47. L

    Help with Allen Head Cap bolts

    Help with Allen Head Cap bolts... Hi, Received today a new headphone amp. It is aluminium construction and uses 4 allen cap bolts at each end to hold the case together. It is all good (was cheap), but the bolts used are clearly low quality and don't look right. I would like to replace them...
  48. E

    Dynamic head, pressure drop formulas?

    My fluid dynamics is rather weak and i was wondering if someone could please tell me how to calculate dynamic head of the flow in the a tube and how to calculate pressure drop of a hole in a tube? Some formulas would be handy thanks engineering
  49. R

    In what direction should the aircraft head?

    Homework Statement The pilot of an aircraft wishes to fly due west in a 50.0 km/h wind blowing toward the south. The speed of the aircraft in the absence of a wind is 205 km/h. a.In what direction should the aircraft head? b. What should its speed be relative to the ground? Homework...
  50. D

    Math Physics Tricky Integrals go Over my Head

    so i have this question about a ladder and the area under it and when it all comes down to it I get the integral, ∫ u2 ( 1 – u2 ) 3/2 du, from u = 0 to u = 1. I am not sure whether to use trig substitution. I keep ending up in the same boat when I do. . . And the same thing when I do...
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