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. S

    Can't detach shaver head (Beurer HR 8000)

    The shaver head in the Beurer HR 8000 (rotary) is supposed to be detachable, so you can swap it with a supplied alternate accessory. But try as I might, I just could't take it off. Does anyone have this model, and have they managed to detach the head? This guy seems to have to struggle a bit...
  2. N

    B Head or Tails: The Question of Determinism and Probability

    I have a question that is bothering me. It is commonly accepted that when playing heads or tails with a fair coin and a large number of tosses are made, the probabilities of getting heads or tails are equal to 50% for each toss. However, the principle of determinism, which states that under the...
  3. paulimerci

    Find momentum transfer and force on the head with and without a helmet

    Without helmet, m = 4kg, ##v_f = 10m/s## ##\Delta t = 0.0005sec## $$ \Delta p = mv_f - mv_i $$ $$ \Delta p_{without} = 40 kg m/s$$ $$ Impulse_ {without} = F_{net} \cdot \Delta t$$ $$ force_{without} = 80000 N$$ With helmet m = 4kg, ##v_f = 10m/s## ##\Delta t = 0.002sec $$ \Delta p = mv_f -...
  4. C

    Determine pump spec necessary to overcome leak

    A vacuum pump is mounted at ground level. The pump is connected to a tree of overhead pipework at a height of 20ft, connected to the pipework are 12 hose reels that can be attached to oil drain tanks. The client requests that the pump be sized so that sufficient vacuum can be achieved to suck...
  5. S

    I Dust sticking to fan blade downstream of rivet head

    Why does dust stick to the fan blades just downstream of the rivet heads, forming a comet-tail like effect?
  6. PaxFinnica96

    Engineering Fluid Dynamics: Proof of the Static Pressure Head equation

    I am trying to mathematically prove the Static Pressure Head equation: H = p/ρg How can I prove this equation and thus determine the nature of the relationship between these variables?
  7. M

    Basic coin toss problem to get 1 head, but with a different method

    Hi, I was watching a video where the following formula, for expected value, was presented for a discrete probability distribution which cannot take negative values: E[X] = \sum_{j = 1}^{\infty} P(X \geq j) and I never saw this formula before and am trying to develop an intuition for it. I am...
  8. R

    How does a pump trade head for flow rate?

    A pump’s power is a product of its pressure rise times volume flow rate. Commonly, a pump is specified by giving the pressure rise, or head, it can provide and the flow rate, such as in gallons per minute(GPM). But some pumps provide the user with a chart that shows how the pressure rise can...
  9. BillTre

    Sea Slug Head Amputates and then Regenerates Body

    NY Times article here. Two species of sea slug (like a snail without a shell) have been shown to be able to amputate their bodies from their heads and then regenerate the body. It is hypothesized that this is done to rid themselves of internal parasites.
  10. Y

    Estimating head loss from pipe slope?

    I am trying to calculate head loss for a sloped pipe. I found this calculation here, which seems to be what I want..or at least a start: https://www.pumpsandsystems.com/pumps/april-2015-calculating-head-loss-pipeline My confusion/skepticism arises from the fact that the equations in the above...
  11. C

    Discovering Drum Head Patterns for Music Education

    Hey everyone - I run a music school and learning about how sound works is really helpful in talking about tone production, volume, and just understanding in general what's going on. As part of that,. I'm looking for a pattern that I could print on a drum head that would show how the head moves...
  12. sahilmm15

    Scratching My Head: Solving a Puzzling Problem

    I am scratching my head on the problem but cannot figure out what to do. I tried in the following way:- For (9) _ _ _ _ _ . The middle place is fixed means only 1 way there. For the first place 9 ways (excluding 0) , second place (9 ways again because 9 digits are left excluding 9 and 0). Third...
  13. iVenky

    B Why does my head feel heavy when I go out on a cold weather day?

    Is it because of increase in pressure on my blood vessels due to cold weather outside?
  14. A

    How to calculate (pump) power to maintain a static head?

    i've this question that i can't seem to work out an answer. supposing that a (centrifuge) pump transfer an amount of energy (power) p to a column of water height h so that it maintains that as a static head. i.e. the water level in that tube is at a fixed height h due to the power transferred...
  15. calvinrose

    B Kill drum head overtones without anything touching the drum head

    Hi All, I considered filing a patent for this invention, but instead decided to publish it so people could use it to advance the state-of-the-art in drums. You don't need to add tape or pillows to your drum heads to muffle the overtones. Using tape or pillows also kills the strike of the...
  16. berkeman

    Improving hearing "Signal to Noise" by turning your head

    I have long found myself turning my head fairly quickly when a noise steps on something I'm trying to hear. Sometimes it is just a noise like a bang or a pop that steps on a conversation I'm listening to, and sometimes it will happen when another person starts to speak and interferes with a...
  17. NathanRB

    Which force acts perpendicular to the side faces of an axe head?

    Say that these pictures are accurate. Personally, I think I can solve this problem, but the issue is, that I had a debate on it with my Physics teacher. This is how my teacher would solve it; my teacher says that each Fk on each side is constructed from half of F and Fx. So, F = 2 * Fk * sin...
  18. T

    How many G forces did I experience during my head hit?

    Hi, I just hit my head on the top of my car door as I was leaving my car; the hit hurt my head a lot and I am worried that I received a concussion. However, I read that most concussions require more than 65 Gs of force to be classified a concussion which is why I am wondering if someone here...
  19. saxman2u

    Pump rainwater into the bottom or top of a tank? Which has the lower head?

    Hi, I have a rainwater collection system where we have to pump water to the main cistern during a rain event. The system works great the way I have designed it and the rainwater is awesome to use in the house and water the plants and grass. The length of pipe I pump the water is almost 300...
  20. jim mcnamara

    Head banging, dancing parrot....

    The researchers associated with this bird claim it has different dance moves,and that the bird has innovated new dance moves over time. The video is halfway down the article, if you want to cut to the chase...
  21. C

    Torque dynamics: Slotted screwdriver head

    See attached image I experienced yesterday that when the slotted screw driver head was exact fit to the slotted screw, it was easier to turn the screw into the hard wood. I'd like to understand the physics of it. Is the bottom (in the picture) easier to turn because there is even contact...
  22. M

    Fluid Mechanics: Head Loss Question (Conceptual)

    I am not really worried about the numbers, but more about the simple concepts with head loss in these pipe flow questions. I want to confirm that head loss just means the change in static head, right? I have been advised that for a problem like this, it is nothing more than the conservation of...
  23. S

    Can't wrap my head around buffers

    Let's keep things simple. I have pure water. pH = 7. I want to add a buffer. I add the weak acid. It dissociates little. So the pH is still close to neutral. So far so good. The problem is, we are also adding conjugate base (the conjugate base is strong). Why doesn't the added base consume the...
  24. sophiecentaur

    The common or garden Dividing Head - how does it work?

    I have looked all over the net and can only find descriptions of how to use a dividing head, followed by countless numerical examples. There must be someone on PF who can give a short algebraic description of the way they work. Machinists as a whole, don't seem to want to present the topic in a...
  25. R

    Hydraulic head as a function of flow rate

    Hello! 1. Homework Statement Symbols and variables: ##\dot{V}## : flow rate ##H## : Hydraulic head ##g = 9.81 \frac{N}{kg}## ##P_{atmosphere} = 101325Pa## ##\rho = 1000\frac{kg}{m^3}## I am given a piping system, with serie and parallel pipes, they start from one point and go back into one...
  26. B

    Suitable net head for a hotel wastewater

    Hi, I am here again. Sorry if this thread is not that related here in this field. I just want to ask, if I have to build a micro hydropower scheme in a wastewater of a hotel, what net head is suitable to use? (Sorry, I can't construct a clear sentence).
  27. jtbell

    Feeling Small at Caesars Head State Park?

    No, I didn't climb a statue. :-p I drove up to Asheville NC today via a slow route and stopped at Caesars Head State Park just before crossing the state line. 180° panorama from the overlook:
  28. ORF

    Why is iron added to the head of a match?

    Hello, The explanation for this, min 0:54 is that you have Fe2O3 in the match head, and after burning it, pure iron is obtained 2 Fe2O3 + 3 C -> 2 Fe + 3 CO2 I think the chemical explanation is fine, but I don't understand why Fe2O3 is added (as colorant, if the red phosphorus is already...
  29. O

    Hydraulic Head Loss (minor) loss coefficient References?

    Hi all, Quick question: What do you guys use as your reference for minor head loss coefficients (k). I'm sure those with more experience have their own database/excels of k values found over the years. I have been personally using a combination of my Hydraulic Engineering Textbook and Google...
  30. José Ricardo

    Medical A shot in the head turn into a man....

    Translation: A man with a mental illness tried to kill himself with a shot in the head. Instead of dying, the bullet struck the part of the brain that caused the mental disorder; he healed and became a great student in college. I know that the page is not there these things. But I have a...
  31. A

    B How do helmets help prevent injury to the head?

    Hi. So I've got an essay I have to write on sports equipment and how they increase safety. I know that in football, equipment to increase safety includes helmets, shoulder pads or paddings and cleats. Unfortunately, I have no idea how each of those equipment work to increase safety. Okay, let's...
  32. T

    Head Calculation of a hot water circulating pump

    Hello, I have the following hot water system. I have a water heater with a pressurized cold water inlet. A re circulation line is taken near the farthest fixture passed through a circulating pump and back to the heater inlet. When calculating pump head, do I calculate pressure drop in the entire...
  33. M

    MHB Probability that we get totally at most 30 times "head"

    Hey! :o A fair coin is tossed $ n $ times; $ X_i = 1 $ denotes the event that "head" appears in the $ i $-th toss. a) How are the single toss $X_i$, $=1, \ldots , n$, distributed? b) How many toss are needed so that the proportion of "head" $\overline{X}_n$ is in the interval $0, 45 <...
  34. Ulle73

    Golf club "Swing Weight" and club head rotation

    for those Who Dont know golf. Swing weight is a measurment how Heavy the clubhead Feels. If i put on a heavier grip the swingweight falls. Heavier head swing weight goes up etc. If i Want to swing the Club with as little clubhead rotation as possible (i know forarm creats the rotation) Would i...
  35. HappyFlower

    Finding the Speed of a head hit by a soccer ball

    Homework Statement When a soccer ball is kicked toward a player and the player deflects the ball by "heading" it, the acceleration of the head during the collision can be significant. Figure 2-38 gives the measured acceleration a(t) of a soccer player's head for a bare head and a helmeted head...
  36. physea

    I Head loss in a circuit of pump and pipes

    Hello! In an experiment (I don't have the details) the predicted head loss in a circuit of pump and pipes was higher as the flow rate increased, than the actual head loss (pressure differential). Can you tell me please what could result in that? What systematically acting factor created an...
  37. K

    Force of impact (ladder to head)

    Hi everyone! need to calculate the impact force done by the ladder to the head explained in the drawing. Can anyone help? Kyrre
  38. D

    Bulb Turbine Head: Inlet, Outlet & Head Explained

    Hi All, My question is about bulb turbines and head. Bulb turbines are used for tidal energy. I guess the inlet and the outlet of the turbine (or the pipe where the turbine is mounted) are both under water. Is head the difference in height between the water surface at the inlet and the water...
  39. M

    Bernoulli's equation, Venturi effect, hydraulic head, nozzle

    Hi, I have this problem: I have a vertical tube 1 meter D, in the bottom end there is a nozzle with 0,5 m D. The tube is full of water. the tube length is 10 meters and the nozzle length is 2 meters. I need to calculate the power of this by this equation: W = Q * g * h * p where W is watt, Q...
  40. B

    MHB Shower Head Jet Separation: Seeking Assurance

    I previously posted this question on this website:https://math.stackexchange.com/questions/2297129/shower-head-jet-separation However, I'm not sure if the answers I got were correct or the answers that I found out were correct, or if neither of them were. Can anyone help assure me which one is...
  41. A

    A NMR Experiments: Why Do I Need a Broadband Probe Head?

    Hello I have to do an nmr experiement. Why do i need a broadband probe head? I have a magnet with 2 tesla. and modulation coils on it with a frequency of 50hz. For example i have a resonance frequency at 50mhz. i hope you can pelp me.
  42. M

    MHB Boat B Must Head 56.4° South of West

    a boat A is heading south at 30 km/hr. its spotted a boat B which is 18 km due east of boat A. boat B has a max speed of 25 km/hr and wishes to get a close as possible to boat A. what direction should boat B head in. so i initially let boat A be the origin heading south. boat B starts at (18,0)...
  43. F

    Centrifugal Pump: Water Pressure at 50m & 4 Bar Gauge

    I have a centrifugal pump 50 m above a vessel, I’m pumping water in at 4 bar gauge into this vessel. I then close a valve to cease pumping ensuring no air enters the system.My question is, if I now open that same valve to atmospheric air this time, will the water exit from the pipe through the...
  44. N

    Algebra Kinematics: Ball above head, how fast must travel to

    Homework Statement Hello there physicsforums, I have a problem that I'd like feedback on as I'm not sure if I had solved it or approached it correctly. A ball that is traveling 5m/s is 30 meters above a person who is standing still. How fast must the person travel in order to catch the ball...
  45. Littlegirloud

    Calculate the diameter of a baby's head using ultrasound speed

    Homework Statement Calculate the diameter of a baby's head if there is a time delay of 96 microseconds between receiving pluses from either side of the skull and the speed of ultrasound can be assumed to be 1250m/s. Homework EquationsThe Attempt at a Solution The diameter of the baby’s head...
  46. H

    Why does the head have it's own inertia during whiplash

    I was wondering why the head has it's own inertia during whiplash when the person is rear ended by another car? I thought that the head would be moving forward also because it is part of the system of the chair being impacted to move forward?
  47. G

    What is the diameter of each hole in the shower head?

    Homework Statement In a low-flow showerhead that contains 18 nozzle holes, the volume flow rate of the water is 4.00 L/min and the water maximum speed is 2.70 m/s. What is the diameter of each hole? Do not ignore viscosity of water. Homework Equations Q=Av_max Q=((pi)r^2)v_max...
  48. T

    MHB Number of possible outcomes where Head is recorded for a coin toss

    A coin is tossed 4 times. Is there a way to determine mathematically what is the probability that exactly 2 heads occur? By drawing a decision tree I can determine that it is 6/16, but this seems like an arduous process for larger numbers.
  49. DaveC426913

    What is the most efficient way to use a pool pump for winterizing?

    I have an above-ground pool which, tis the season for draining and winterizing. I have a 15 foot section of ribbed pool hose (designed for pumping) that I hook up to the pump and flush the pool with. Pool is 4 feet deep both inside and outside, with a 1foot lip. Hose needs to rise one foot...
  50. M

    A Head Injury at Swimming Pool: Are Pool Tiles at Risk?

    Is due to a collision between the head of the 20-man wall at the swimming pool can crack the back of the pool as in the following picture? Professional anyone who knows the man's skull and pool tiles? I just swam back and crashed against the pool with his head, and since I'm in pain and cervical...