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. L

    MHB Why Do Physics Equations Confuse Me So Much?

    My brain feels like goop after reading these. I am struggling big time! Help is greatly appreciated. Q1: The formula s=(u+v)/2t works out the distance traveled by an accelerating car (s), where u is the inital velocity, v is the final velocity and t is the time interval. a) Transpose the...
  2. Celestion

    How do you divide polynomials in your head "on sight"?

    Homework Statement The question was to find the roots of x3 - 3x2 + 4x - 2 = 0 Homework Equations The first root is found by the factor theorem, substituting x=1 into the polynomial gives 0 therefore x=1 is one root and (x-1) is a factor. The Attempt at a Solution In the worked solution...
  3. M

    Some questions on pressure drops and head loss in pipe flow

    I would like to ask you that why pressure drop is constant through pipe? How can we know that dP/dx=constant? Thank you.
  4. F

    Understanding the Formulas for Major Head Loss in Pipes

    Homework Statement why the author use major loss due to fluid friction is fL(Q^2) / 3(d^5) ? according to darcy weisbech , the major loss due to friction has the formula of fL(v^2) / 2gD why the author wrote it as fL(Q^2) / 3(d^5) ? I don't understand Homework EquationsThe Attempt at a...
  5. F

    How does pipe thickness affect head loss at entrance?

    Homework Statement I was told that for loss of head at entrance , the degree of contaction depends on how thick the pipe walls is . i really don't know the meaning , can someone clarify ? the author also stated that the loss coefficients will vary , for very thin tubes , k is very high ? head...
  6. E

    Calculating pump head required

    Homework Statement I need to calculate the pump head required for a fluid transfer system. The pump is located 3m above a storage vessel vented to atmosphere (1 bar) with a total pipe length of 5m to pump suction. The pump discharge is connected to a pressurised vessel at 2 bar absolute with...
  7. R

    Conservation of linear & angular momentum head on collision

    Homework Statement Two cars collide head on but offset from each others center of gravity. After the impact the two cars are locked together as one body. Due to the location of the collision point, the impact causes the two locked cars to spin clockwise. Car A- traveling west going 10 mph...
  8. F

    Calculating Major Head Loss Due to Pipe Friction

    1. The problem statement, all variables and given/known i am having problem of finding the major loss caused by pipe friction in this question. the formula of major loss is given by fL(V^2) / 2gD , how to get the total length of pipe so that i can gt the major head loss? . Relevant equationsThe...
  9. G

    Calculate head loss per meter clarification

    Calculate the head loss per metre length of a capillary tube which has a bore radius of 0.45 mm when a fluid of density 850 kg/m3 and viscosity of 25 cP is flowing at a rate of 50 l/hr. State whether the flow is turbulent or laminar. I have attached my attempt at a solution using poiseuille's...
  10. R

    Fluids: Energy equation involving head loss

    Homework Statement See attached image: Homework Equations p/ρg + V^2/2g + z = constant head loss (major) = f * l/D * V^2/2gThe Attempt at a Solution To use the energy equation while incorporating head loss, I need to determine the velocity in each section of pipe. The problem is I don't know...
  11. F

    How to calculate head loss in a pipe with sudden diameter expansion?

    Homework Statement estimate the energy head lost along a short length of pipe suddenly enlarging a diameter of 350mm to 700mm which discharges 0.7(m^-3) of water per second . the solution given is Q1= Q2 = 0.7(m^3)/s 0.7 = pi ((350x10^-3)^2 ) V1 / 4 , V1= 7.28m/s 0.7 = pi ((700x10^-3)^2 ) V2 /...
  12. F

    How Do You Calculate Head Loss in a Venturi Meter Using Bernoulli's Equation?

    Homework Statement A venturi meter is being calibrated horizontally and has a diameter of 75mm at the entrance and 50mm at the throat . The flow rate is obtained by measuring the time required to collect certain amount of water . The average number of measurement gives 0.614m^3 of water in...
  13. M

    Head Loss and Pressure Rise During Gradual Expansion

    Homework Statement , There is an Head Loss question, two pipes join and expanding parts 30 degrees from the horizantal. Homework Equations The Attempt at a Solution Before attemting a solution I try to understand what a1=a2=1.06 is? Would you like to give some information about it...
  14. F

    Loss of head at submerged discharge

    Homework Statement in the notes , author said that the velocity within it is negligible? does the author mean the water velocity in the tank ? so the velocity (v^2)/2g in the 4.24 means the velocity in the pipe ? Homework EquationsThe Attempt at a Solution
  15. V

    B Turning Einstein’s train thought experiment on its head

    Let us first review Einstein’s train and platform thought experiment which consists of one observer midway inside a speeding train car and another observer standing on a platform as the train moves past. A flash of light is given off at the center of the train car just as the two observers pass...
  16. F

    Head loss formula in series pipe

    Homework Statement i know that the formula of head loss is (V^2) / 2g , where v =velocity , but , why did the author want to change it to k[(Q)^1/n ] ? Homework EquationsThe Attempt at a Solution
  17. Mingsliced

    Fluid Mechanics - Head Loss Due to Friction

    Homework Statement This is simply a sanity check concerning the system described and attached. My concerns are detailed within my attempts at the solution. Any guidance will be greatly appreciated! The diagram attached represents a process for which a pump and associated pipe work require to...
  18. P

    GeForce Impact: Tennis Ball Hits Head

    I have a question concerning GeForces. imagine a tennis ball that weighs 57 Gramm Hits a human head that weighs 4 Kilogramm on the forehead, at a speed of 120 kilometers per hour. the head moves back 15 centimeters until it stops because of the resistance of the spine. how much g-force did the...
  19. Kevin McHugh

    Solve Reimann Curvature: Diff Geom Tips for Computing 256 Components

    Should I post in Diff Geometry? I searched that forum, and did not see what I was looking for. I want to compute all 256 components of the curvature tensor. Do I start with the equation of geodesic deviation in component form, or can I go straight to the definition of the components in terms of...
  20. TheMathNoob

    I can't do arithmetic operations in my head quickly

    I am currently in upper division math courses in my career and I can't do something like 109-64 quickly in my head. I obviously try to break every number apart to make hard subtractions, but I can't do it fast!. Should I worry about this?. Overall, I have done well in my math life, but I feel...
  21. W

    Head Loss Formula: Gamma Meaning Explained

    Homework Statement what does the gamma in the formula mean ? since the other terms in the formula are the same , i can just cancel it, leaving μ / γ = v /g . So , γ has unit of kg(m^-2)(s^-2) ? Homework EquationsThe Attempt at a Solution
  22. F

    Lamp tips over and hits the top of the head

    Imagine a lamp tips over and hitst the top of the head. the lamp weighs about 300 gram and the distance when it started to tip over and hit the head was about 15 centimeters. in the moment of the impact the lamp has tipped over excactly for 90 degrees. The material is Metal that deforms only...
  23. M

    Find Mass 2 with Momentum Conservation

    Homework Statement Hockey player 1 is traveling at a velocity of 12m/s North and hockey player 2 is traveling at a velocity of 18m/s south when they collide head on. after colliding, the hockey players hang onto each other and slide along the ice with a velocity of 4m/s. if hockey player 1...
  24. C

    Finding Final Velocities in head-on Collision

    Homework Statement Two balls move toward each other. Ball one is moving in the positive direction, has a mass of m1, and a velocity of v initially. While ball two has a mass of m1/2, is moving in the negative direction, and has initial velocity of v2. Once the collision takes place ball one...
  25. KrisOhn

    Head loss equaling head pressure?

    If you had a fluid in a pipe, with say, 10m of head pressure, what would happen when the head losses of the pipe equaled the head pressure?
  26. K

    Distance traveled during a head on collision

    Homework Statement During the head on collision of a 1500kg car moving 20 m/s and a 2400 kg truck moving 12.5 m/s does the car move farther than, a shorter distance than, the same distance as the truck, or is this indeterminate with the given information. Homework Equations...
  27. Junjou

    What angle should the bird head?

    Homework Statement Canada geese migrate essentially along a north-south direction for well over a thousand kilometers in some cases, traveling at speeds up to about 100 km/h. The one goose is flying at 100 km/h relative to the air but a 34 km/h wind is blowing from west to east. At what angle...
  28. A

    Rotating sprinkler head and torque

    Hi, can anyone tell me where this "shaft torque" is coming? What is causing this torque? Screenshot is from Fundamentals of Fluid Mechanics by Munsun. http://postimg.org/image/3zilpmzbv/ Thank you.
  29. Zephyr007

    Viruses: A pain in the head and my laptop.

    Hi, My laptop is a Lenovo G450 and I use Windows 7. After I downloaded a Mp3, viruses just joined in my laptop. I saw unwanted ads in Google. I removed SeallePlus and DownSavve in the extensions but it keeps coming back. I use Symantec Endpoint System but it takes long to have a full scan...
  30. F

    G force calculation of hitting the head

    Hello, Could you guys please do me a favor and calc the g force of a 8.8lbs head that accelerates with 1m/s or 1.5m/s and than hits a solid metal objebt with the back of the head which moves 0.5 mm. This is no homework. It happened to me.
  31. halfgt2

    Pump Head & Suction (leaky closed system) PF Newbie

    Hi physicists! I am scratching my head to remember the most basic laws of fluid flow while I try to irrigate things from a barrel. Not exactly rocket science, I know ;-) But very exciting for me ... The situation is simply a pump (cheap submersible one) put into a barrel (sitting on the...
  32. R

    Medical How can I detect and stop voice attacks in my head?

    Hello, I have a strange question: One day i drinked with few persons with which it was not really good thing to drink (criminals), after few days i started to hear strange voice projected like it would be from my phone which was saying "you're dead", I am 100% sure that I am not shizophrenic...
  33. makkhi

    What is phased array head and neck coil in MRI?

    I was reading this article " The Effect of Head Rotation on the Geometry and Hemodynamics of Healthy Vertebral Arteries" They used an MRI machine with a phased array head-neckcoil and a phased array superficial coil. what are they?
  34. P

    What is the peizometric head difference between A and B?

    Homework Statement Water flows in an inclined pipeline in an upward direction from A to B. A differential U-tube manometer is connected between A and B and indicates a mercury level difference of 30 cm. The difference in elevation between A and B is 2 m. What is the peizometric head...
  35. thankz

    Off the top of your head can someone name a pic micro....

    off the top of your head can someone name a pic micro that has a adc, Ethernet and open tcp stack available for it. preferably in dip package, 40 pin is all my programmer can handle. I figure I should do something with my time so why not get started on my aquarium project.
  36. X

    Trouble wrapping my head around GR

    So, I feel like I have a pretty good grasp of Special Relativity, but GR is a whole different beast. I am really stuck on where the acceleration comes from for Gravity. For instance, it's easy for me to understand how an orbit can form from bent space (an analogy for the way I think of it is a...
  37. Dennis C

    Pump NPSHA (net positive suction head) question

    Simple (I hope) pump question. With the pump not even running, would like to know what my static NPSHa is if I had a flooded pump suction with 10 feet suction head of water and a vacuum of 27" Hg above the water? Basically it is the hotwell from a condensing turbine exhaust after the steam...
  38. N

    How much of a head start does B need to win the race?

    Hey all. Simple problem here. 2 people are running at 2 different speeds in a race 50m long (A at 5 m/s B at 3 m/s), A is clearly going to win, How much of a head start would B need to win? (This isn't a homework problem I'm just wondering how long I have to wait for my movie to buffer before I...
  39. gracy

    Head on Collision: Conservation of Momentum Explained

    My teacher taught us conservation of momentum.She gave us an example (or way to think )as if one of the blocks has spring attached to it.As given in the image.As u1 >u2 there will be collision ,though surface is not shown it is assumed to be smooth so that friction does not act,this is...
  40. T

    Thermofluids, bernoullis equation head loss

    Hi, I just have a few questions on bernoullis equation dealing with power and head loss If the equation for power is p = mass flow rate * g * Hloss, Then is g only used when let's say a pipe is at an elevation ?, because in my book I have an example where g is not used to calculate the power...
  41. FJ Moose

    Off-Road Snorkel head direction, does it matter?

    I know very little about physics, but I have a question. What are the effects of turning an off road snorkel head backwards (facing the rear of the vehicle)? We on the FJ Cruiser forums are debating, and I thought I would ask the experts :) Some of the concerns/debates include: reduced air...
  42. F

    How much g's creates a 100 lbs punch to the head?

    Hi guys, I heard in the news today that a punch of a pro boxer can create about 50 g. I was just wondering how much g's a rather weak punch(100 lbs) can create?
  43. H

    Final velocities from head elastic head on collisions

    Homework Statement Ball A with velocity +3.00 m/s collides with ball B with equal mass traveling at -2.00 m/s. What is the velocity of each ball after the collision. Homework Equations Not sure. The Attempt at a Solution I know that momentum is conserved because, but solving the conservation...
  44. CFDFEAGURU

    I Don't Like Mondays: How Boomtown Rats Got Stuck in My Head

    Somehow I managed to get the Boomtown Rats - I Don't Like Mondays, stuck in my head
  45. O

    Automotive Force on dog's head out of car sunfoof

    (i have made this thread as i previously had it in the aero section and it was probably not getting the attention such an important question deserves.) lets use the sunroof as an example for simplicity. what force is the wind acting on the dog at 50mph/22.3m/s? dog head diameter = 0.2m...
  46. F

    Can't get my head around reduced mass (particle physics)

    I know it's probably simple but I just don't understand reduced mass. I am trying to work out the reduced mass of 4He+. m = memN / me + mN Can somebody please just explain step by step what I do. This is only a segment of a 1 mark question and I'm getting my knickers in a frustratingly twisty...
  47. A

    Estimate pipe diameter based on flow rate

    I'm designing a testing unit where I need to estimate the smallest diameter of a short complex pipe (around 1 meter, three bends and some diameter viariations). Since the pipe is being cooled down in a water bath after production, my idea is to force water with a known pressure in one end of the...
  48. P

    Can you reconstruct a 3d head from just two photos?

    hello! is there a way to reconstruct a whole head, by having a profil and enface photo of the person? thanks!
  49. A

    Fluid dynamics: head losses and pressure

    see I worked through 3a) and I was comparing answers, I saw that they omitted v2 (5m/s) their explanation was because it was "defined in the question" I'm not sure what that means 3)b I tried understanding what's going on but I am clueless unfortunately, how exactly did they get 12.1m ? Where is...
  50. E

    Does the flow rate and pressure decrease as the exit height of a pump increases?

    OK, So I have been having an on and off debate with my family about this. I saw a pump at Home Depot that said it has a 30 ft head. Then it went on to show that the flow rate varied as the output of the pump changed in height. Now I thought that this was wrong. I just finished a course in...
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