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. I_am_learning

    How Can the Weight of a Human Head be Measured?

    Just in the middle of random discussion with my friend, we wondered how could the weight of a human head (the portion above neck) be measured? Of-course without doing nasty things. (eg. chopping. :devil: )
  2. M

    Medical Body and head hair differ, why?

    Why does head and body hair differ? Doesn't monkeys have the same type of hair on their head and the rest of their body?
  3. H

    Human head gives off smoke when electrocuted?

    I heard that when any human being is executed by electrocution (for instance on an electric chair) afterwards, smoke comes out of his head (seriously). Why does this happen? I think it's got to do with the fact that the human head has a huge number of neurons and their is a lot of electrical...
  4. W

    Flow rate and available head relation

    It is stated that as volumetric flow rate increses the available head decreases. Can anybody explain this sentence?
  5. D

    What is the optimal torque angle for hardened head studs in a vehicle?

    Hi, can't believe I haven't discovered this forum until now - I would post in an introductions section, however I couldn't find one! This question is loosely based around mechanical engineering, however may be applied to automotive, so apologies for posting in the wrong section. I have had a...
  6. V

    Archived Fluid Mechanics - Piezometric Head

    Homework Statement Homework Equations Provided above The Attempt at a Solution Piezometric head is defined as the pressure head plus the elevation head, correct? But how does having a high piezometric head tell you about the fluid flow? Since the diameters are equal, the area's are...
  7. J

    Good way to get a head start on ODE's?

    Hey guys, I'll take ordinary differential equations this summer. Class starts on June 4th. I wanted to get a head start on the topic because i'll take it with a professor that usually gives VERY hard exams, and I was wondering if anyone could recommend me a good site or something to start...
  8. Z

    Really Hard(for me) head on collision question

    Homework Statement A snooker ball hits another one of the same mass head-on.If a quarter of the initial kinetic energy is dissipated in the collision ,what is the coefficient of restitution? Homework Equations Ei=Ef The Attempt at a Solution Energy statement: ua+ub=(3/4)*(Va+Vb) Momentum...
  9. H

    Tossing a coin until it lands head up

    A coin with unknown probability p of landing head up when tossed, was tossed until it first landed head up. It happened on the 5th toss. Describe an appropriate statistical model for this experiment and write down the observed Likelihood function L(p). I assumed this was the same as...
  10. Spinnor

    Slow mo walking chicken video, watch the head movement.

    The video, http://www.youtube.com/watch?v=XDCk0DaNwiQ&feature=results_video&playnext=1&list=PL28AFB6F1D7079B62 Observation of our chickens, when a chicken walks the head is kept motionless and then moves quickly to a new position, repeating over and over again as the chicken moves forward...
  11. Evo

    Quietest place on Earth messes with your head

    I think I could handle it. How about you? http://games.yahoo.com/blogs/unplugged/quietest-place-earth-mutes-sounds-messes-head-212556719.html
  12. W

    Held magnetic device close to head dangerous?

    So I briefly rested the side of my head on the back of my iPad. It had its magnetic smart cover attached, which has many small rare Earth permanent magnets (type of magnets unconfirmed). My head was rested near the speaker (having its own magnetic properties) and smart cover magnetic...
  13. M

    Investigating Orifice Problem: Pipe Head Differences & Theoretical Head

    Orifice problem I've been given a list of quantities Pipe before orifice head = 255mm Diameter = 31.75mm Pipe after orifice head = 230mm Diameter= 20mm Time for 10litres to fill in collection tank 67.09seconds Assuming g= 9.81 and density = 1000 from the experiment difference in...
  14. M

    Medical Why do we have head aches? Our brains can't feel anything.

    I often wonder how do we have head aches, when the brain does not posses the ability to experience pain. The yahoo answers are faintly useful, so I decided to put one here. Someone told me that, the head ache, is related to a muscle being sore. For instance, if my forehead is aching, it means...
  15. A

    Modelling the sound of a drum head.

    Please excuse me if this is not the most appropriate subforum for this question and please move it if necessary. I am trying to make a numerical model with Mathematica to synthesize the sound of a struck drum head (circular membrane). I solve the wave equation for a circular membrane to get a...
  16. B

    Max weight that anyone can lift using over head pulley.

    Can a man whose weight is 50KG (but powerful arms) lift another man with 70 KG weight using an overhead pulley. I guess no since the light man is not clamped to the groud, his arm strength will not bear any significance and he can lift only the wieght(on other side of the pulley) equal to his...
  17. T

    Tough Math problem, above my head, any help much appreciated.

    Homework Statement Essesntially me and my friend for our physics ISP (which is like a final project in ontario) are building this gravitational torsional balance: http://www.fourmilab.ch/gravitation/foobar/ Our set up is very similar, with our main balance arm being 30cm long , 5cm wide and...
  18. P

    How can the velocity at points of change in pipe systems be determined?

    For minor losses, I read that the pressure drop is equal to the dynamic pressure * loss coefficient. However, in calculating dynamic pressure, it uses a single velocity. How do you determine this velocity when it will vary at the point of change in pipe diameter or direction? I have read...
  19. J

    Calculating Head Losses through a Pipe Network

    Hey everyone! I'm trying to determine the losses through a pipe network that consists of 254.5 feet of 0.75 inch diameter copper pipe. The flow rate is 0.37125 gpm, with a corresponding velocity of 0.26962 fps. The fluid is water at 150 degrees F. Based off that information, I have a...
  20. O

    Trying desparately to wrap my head around proportional relationships

    Homework Statement A) Suppose that we have 3 quantities, x, y, and z. An increase in x by a factor of F is followed by a subsequent increase of y by a factor of 2F. Furthermore, the very same increase in x by a factor of F results in a subsequent decrease of z by a factor of F/2. Similarly...
  21. B

    Impulse of Soccer Ball on Head

    Homework Statement Recent studies have raised concern about 'heading' in youth soccer (i.e., hitting the ball with the head). A soccer player 'heads' a size 5 ball deflecting it by 31.0°, and keeps its speed of 10.40 m/s constant. A size 5 ball has a mass of approximately 0.446 kg. What is the...
  22. J

    In Over My Head - Senior Design

    So I thought it would be fun to try to learn about digital image processing for my senior design. My group decided to make a robot that would find a ball and pick it up into a rack. Well, two people in my group was tasked with figuring out the mechanics or the robot, which they did fine, but I'm...
  23. N

    Sequence and series - Arithmetic mean question have been breaking my head

    Homework Statement Two consecutive numbers from 1,2,3...n are removed A.M of remaining numbers is 105/4. Find n and those numbers removed .Homework Equations Answer n = 50 those numbers are 7 and 8 The Attempt at a Solution I solved this question like a few weeks ago but now it escaped my...
  24. G

    Find the angle the boat has to head

    Homework Statement A boat, which can travel at 8.2 m/s in still water, heads directly across a river which has a current of 4.5 m/s and is 477 meters wide. What should the heading of the boat be in order for it to land at a point on the opposite shore exactly 100 m upstream from the starting...
  25. D

    How do you head up a big can of plastic?

    I have a cylinder of plastic (polypropylene). It is 1 meter in diameter and 1.25 meters long. It starts out at an even temperature of 100 C throughout. I put it into a 135 deg heated room with lots of air moving around it, and I hold it in the air so that every surface is exposed to the hot...
  26. G

    Studying for Head and Neck Anatomy Exam: Cranial Nerves

    Ok so I have a huge exam tomorrow on head and neck anatomy :cry:. Learning the cranial nerves thus far has been a beast. I just wanted to make sure I have this correct, ALL somatic cranial nerve fibers, and ALL sympathetic cranial nerve fibers are postsynaptic correct? The only nerve fibers...
  27. S

    Messing up simplifying formula for head on collision problem

    Ok I have been going crazy and I think I must be making a simple algebra mistake. Basically in my book I read over an example dealing with a head on collision between 2 balls and the collision is elastic so the kinetic energy intial= final KE. The momentum is also conserved so i can use momentum...
  28. M

    Energy Loss in Head on Collision of Two Cars w/Same Speed and Mass

    Homework Statement Two railroad cars, each with a mass of 7,000kg and traveling at 90 km/h collide head on and come to rest. How much mechanical energy is lost in this collision? Homework Equations KE=\frac{1}{2}mv^2 The Attempt at a Solution...
  29. E

    Don't bite my head off here right away, I'm only a high school

    Don't bite my head off here right away, I'm only a high school student. I was thinking about the vacuum of space, and to me it just seems odd that there's nothing there. If there was really nothing there, would it really exist? Absolute zero does not exist, there's no space, time or anything...
  30. N

    Fluids question - Pump flowrate ofdue to elevation head

    Hey guys, I've been strugling with a concept recently and was hoping someone familiar with fluid dynamics could answer. I am trying to calculate the flowrate of a flow circuit with a given pump. I have the pump performance curve (flow vs. head) of the pump and I know all the given pipe...
  31. O

    Help getting projectile motion equations straight in my head

    Homework Statement In the figure, you throw a ball toward a wall at speed 26.0 m/s and at angle θ0 = 37.0˚ above the horizontal. The wall is distance d = 17.0 m from the release point of the ball. (a) How far above the release point does the ball hit the wall? What are the (b) horizontal and...
  32. P

    Schools In graduate school for electrical engineering classes over my head

    So I graduated in undergrad in May 2008 with a BS in EE. I went directly into a PhD program with full funding. I put in a year and did decent in my classes and my research. But I didn't enjoy my research and I wasn't doing as well in my classes as I had hoped. I decided to take a leave of...
  33. C

    Head on collision between mirror image vehicles

    I have a question and I would like some help. Assuming mirror image vehicles hitting at 65mph. Is the force exacted on each vehicle equal to 130mph or 65 mph. My assumption is that it would be the same as hitting an inelastic brick wall.. Thank ya'll in advance..
  34. A

    Medical Effect of applying oil to head and having oil bath

    In our place people use to apply vegetable oil for head,( and to body at times) and have a bath after half an hour or so. They say it keeps them cool. A kind of effect induced by mint shampoo. I don't understand how it works. But would love to know it.
  35. T

    Can't get my head into vector spaces and subspaces

    Hi, I'm new to linear algebra. I'm pretty good at doing exercises with matrices and stuff but even though I've been looking in different books, looking all over the internet I can't get into vector spaces and subspaces. It seems like the books have some very elementary and simple examples and...
  36. M

    Solving Chapter 3 Problems in "How to Prove It

    Two problems from chapter 3 of "How to Prove It" I just cannot get my head around The thing I hate about proving things is that I can always think it through in my head, but don't know how to express it mathematically for a sound proof. Homework Statement 7) Suppose a, b, c, and d are real...
  37. B

    Understanding Pump Capacity at 30m Head

    a pump capacity of 10 m^3/hr at 30 meters head. what does the 30 meters head mean? thank you..
  38. R

    Medical Living Head in a Vat: Exploring Transplant Possibilities for Terminal Patients

    For those with terminal cancers or diseases of the body with intact brain. And noting that the purpose of the body is just to support the brain. How come they don't transfer the head of a bodily terminally ill person to a artificial heart-lung-dialysis, etc. all in one machine such that blood...
  39. J

    Are Helmets Really Effective in Preventing Head Injuries from Bike Accidents?

    i work in a bike shop - i am always getting questions about helmets - what good are they as they are only made of foam - i have been trying to find a way to explain just how fast your head is going when it hits the ground when you fall off a bike and what force is exerted upon your 10 pound...
  40. A

    Gravitational Time Dilation - Is my head older than my feet?

    According to general relativity, objects in a strong uniform gravitational field experience time slower that objects in a weak uniform gravitational field. Does this mean that my feet, being closer to the Earth that my head, are younger than my head when I die? If this is correct could someone...
  41. K

    Love playing Playstation to get my head free - childish or allright?

    Hey, I've noticed that especially when I have to do some serious work (like studying for an examn as the deadline gets closer) I play Playstation a lot. I have an old Playstation 2 in my living room and whenever I feel overwhelmed or stuck or just as a reward for having made progress in my...
  42. P

    Maximum flow rates through water turbines given power and head.

    Homework Statement Calculate the maximum flow rates through the Francis and the Samson turbines under the conditions specified: Table 1 Characteristics of some American water turbines, 1849–97, on the basis of 30-inch (760 mm) wheel and 12-inch (300 mm) head Type | Maximum power output...
  43. K

    Varying head rise in Centrifugal pumps

    Hi PF! I have a question regarding the use of centrifugal pumps. I have a system with a constant flowrate of water at 2m^3/s pumping water from a lower to a higher reservoir. The inlet condition is a head of 10m. The Height of the upper reservoir will vary from 83m in the beginning to 287m...
  44. B

    Elementary probability problem I can't get my head round Help

    There is a bag in front of me. I am told it contains 100 red balls or 50 red balls and 50 blue balls. If I pick n red balls from the bag and no blue balls what is the probability as a function of n (p(n)) that the bag contains 50 red balls and 50 blue balls. Of course, if n is greater than 50...
  45. nukeman

    *2 trucks each going 50km/m hit head on with a force of still 50km/h ?

    *2 trucks each going 50km/m hit head on with a force of still 50km/h ? Hey all, I am a first year physics student, and want some more info on this one here. I heard it in a lecture. Everyone thinks that if 2 trucks are each going 50km/h and hit head on, it would be the same as a single...
  46. S

    Foxhole radio problems that are way over my head

    Homework Statement A radio station transmits 680kHz at a power of 50000W from a transmitter. Estimate the strength of the signal as it was received by the antenna 35 km away. Homework Equations I don't know any equation for this that's the problem! The Attempt at a Solution I can't...
  47. S

    3.5 FDD head size: size of the gap of the read/write heads

    3.5" FDD head size: size of the gap of the read/write heads I doubt anyone here knows the answer, but I thought I would ask anyway. I mean, I know not of a better forum on which to ask... Anyway, does anyone happen to know the size of the gap of the read/write heads of a 3.5" floppy disk...
  48. Ryan_m_b

    When an idea pops fully formed into your head

    Something's been bugging me lately. A while ago I read a book on consciousness (A very short introduction by Susan Blackmore) that outlined a term for when an idea get's subconsciously worked out and then arrives fully formed in your conscious. You know the type of thing when a problem at...
  49. D

    Total pressure head in a pipe

    Homework Statement In a water treatment plant, a 30cm pipe carries raw water at a rate of 6m3/min. The pressure at a given point is 3.5 bar. If that point is 10m above the datum line, calculate the total head at that point in a) m of water b) m of HgHomework Equations Z + \frac{P}{\rho...
  50. F

    Medical What is the Scientific Evidence for the Best Diet?

    I just finished watching the documentary "Fat Head" and I was very surprised (and confused) about the outcome. Long story short, if you haven't watched it, a guy goes on a fast food diet for a month (much like Morgan Spurlock) but he ends up losing 15 lbs. And all the while he goes through these...
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