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. E

    Train Collision Problem - Calculating Head Start

    Homework Statement The engineer of a passenger train traveling at 25.0 m/s sights a freight train whose caboose is 200 m ahead on the same track. The freight train is traveling at 15.0 m/s in the same direction as the passenger train. The engineer of the passenger train immediately applies...
  2. D

    Calculate Pump Static Head - New User Guide

    I am new to pumps and wondering how to calculate the total static head for the system below.
  3. N

    Water to air heat exchange - imperial units doing my head in

    Hey guys, newbie here and first post. I've got a (hopefully) simple question, but for some reason my brain just isn't working. I'm too used to working with metric, and even though it should be fairly simple, working with imperial units just hurts. Anyway, here's the problem: I have a specific...
  4. T

    Why Does My Inductive Impedance Calculation Seem Incorrect?

    Hi guys, Firstly I apologise that I'm even asking this... I have gone over it so many times now I don't know what to believe is the right answer, can someone please help me out and let me know where I'm going wrong PLEASE Ok so first is the inductive impedance Z= SQRT R^2 + (WL)^2 R...
  5. R

    Pump head requirement: Closed vs Open loop

    If a pump pumps water to a heat exchanger at a certain height, say, 20 m is the head required indeed lower for a closed loop system than an open loop system? The link below says so, but I wanted to verify. Assume pipe friction losses are the same in both cases. Can one really take credit for...
  6. R

    Pressure problem - Impulse of object striking a head

    Pressure problem -- Impulse of object striking a head 1. A police crime lab is trying to determine whether someone was murdered or died as a result of an accident. He was struck in the temple by a 4.20 kg sculpture that is alleged to have fallen off a bookcase. The sculpture presumably fell a...
  7. B

    Head pressure for liquid in a tank

    Did I answer this right ? An open tank contains liquid with a specific gravity of 1.735. If the height of the liquid is 10 feet, how much head pressure (in inches w.c. (water column)) will it exert? P= (10) (1.735)= 17.35 What is the pressure in PSI? P= (1.735)(0.433)(10feet)= 7.51255
  8. M

    Which Water Tank Piston Requires More Force?

    It may be a simple question to you but I need help understanding head pressure and I need to set things up to ask it. Assume two 4 ft diameter by 25 ft tall water tanks, both are equally filled to 23 ft. Both tanks have chambers of the same diameter as the tank attached below them. Each...
  9. C

    Minor head loss for turbulent vs. laminar fluid flow

    Hi, I need clarification on the difference in head loss for turbulent flow and laminar flow. I understand how the head loss due to friction is different for the two regimes. For friction head loss, the friction factor is 64/Re for laminar flow, and a more complex formula for turbulent flow. I...
  10. K

    Negative pressure head in a nozzle

    Hi, I am doing some fluid flow calculations for some nozzle designs at work. For one nozzle in particular, the fluid flows through an inlet pipe, then flows through a short contracted section, then flows into a Helmholtz chamber before entering another contracted section through which it...
  11. N

    What is the force of a head on collision between a jeep and a bus?

    Hello. I'm a writer going back and doing some fact checking to make an important scene more believable. It involves a character, Lux in the backseat of a jeep which has just suffered a head on collision with a bus. But I think I am doing something wrong because the numbers I get don't seem to...
  12. D

    What has Euler got on his head here?

    This is a very well-known portrait of Leonhard Euler, which I'm sure most people have seen before, but does anyone know what the heck he's wearing on his head? http://upload.wikimedia.org/wikipedia/commons/d/d7/Leonhard_Euler.jpg It looks like someone threw a dirty old rag on him - does anyone...
  13. T

    How to get a head start to grade 11?

    Grade 11 courses to become a pediatrician Hi, I would like to pursue a career in the medical area and would like to become a pediatrician. I just submitted my courses for grade 11...and I would like to go to mcmaster university. Here are my courses: 1. Functions (math) 2. Chemistry 3...
  14. Ascendant78

    Is it typical for some physics (math) to go over your head at first?

    Long story short, I just finished Physics I. Since I'm currently attending a state college, I have been trying to study outside of my coursework in order to optimize my education and have the best chance of getting into top grad schools. One of the resources I was trying to use was MIT's...
  15. K

    Conservation of Momentum in Partially Elastic Collisions: Solving for Velocity

    Homework Statement In the figure shown, a ball of mass m collides perpendicularly on a smooth stationary wedge of mass M, kept on a smooth horizontal plane. If the coefficient of restitution of collision is e, then determine the velocity of the wedge after collision. Homework Equations...
  16. A

    Calculating Pump Head: Equation & Parameters Explained

    Hi there Looking for some help with calculating the head for a pump The example in my textbook isn't exactly clear. Is there a specific equation I can be using or can it be worked out having the following: volumetric flow rate density of fluid gravity pump efficiency pipe...
  17. T

    Head added and final pressure

    1. Homework Statement Given: A sealed, rigid container (cannot change shape or size) containing steam at the shown conditions has heat added until it reaches the final shown state. Determine: a) heat added, b) work performed, c) change in internal energy of the system, and d) final system...
  18. R

    Piping pressure head estimation

    Say there's a pipe that pumps a liquid that empties into an elevated tank The discharge end of the pipe is 5 m higher up than the suction but it goes over an intermediate obstacle, say, 20 m higher than suction level. Is the pump head requirement 5m or 20m? I'm confused. My gut feeling...
  19. A

    How Can I Calculate the Head Increase of a Rotating Object Underwater?

    Homework Statement Hi all I have an object (which has valves attached) underwater which rotates from a starting point of 17 degrees to 0 , as the object rotates the hydrostatic head on the valves increases over time. how can I calculate the head increase over a time period (per 10...
  20. C

    Wing pitching moment ( torque not around cg ) - head hurts

    Wing pitching moment ( torque not around cg ) - head hurts! Hi all! :) First post! I am currently coding up a basic flight simulator for fun. It is all going well so far - and certainly improving my rusty physics knowledge. I break the wing down into elements calculate the lift and drag on...
  21. B

    Momentum conservation law: Head on elastic collision

    Hi guys, I've been thinking on a problem for a while which really bothers me. I've been trying to mathematically solve the following problem: A train approaches the station at a velocity of V=50 m/s. Then a tennis ball is thrown with a velocity U=30 m/s, against the approaching train...
  22. G

    Combinatorics head check

    Homework Statement Peter and Simon shares a bag of 11 fruits, of which 3 are poisoned. Peter eats 4 fruits, Simon eats 3 and their dog eats 1 fruit. What is the probability that both Peter and Simon gets poisoned, given that the dog ate a healthy fruit? Homework Equations The...
  23. J

    Real-World question i can't get my head around.

    I am going to feel silly when you guys give me the answer in 2 seconds but here we go. Imagine there are 16 rectangular pieces of paper with length 2 and width 1. You want to organise them in a big square or make them fit the smallest area possible. How many columns do you have and how...
  24. P

    How to develop a RAM Pump with a 300m delivery head?

    Hey there, I was just wondering if its actually possible to configure a RAM Pump to deliver up to a height of 300m (984 ft) I've made a ram that has a delivery head of 35m (115ft) for personal use; however a family friend wants me to set up a RAM for them that goes up to 250m and...
  25. M

    Trying to understand the whole picture in my head.

    Homework Statement so.. I'm taking a electrotechnical engeneering at university and now I'm talking a lot about telecomunitactions and i find myself working with Fourier transforms and laplace transforms, and majorly, the e^(jx)... and this last one shakes up my concept of the usual number...
  26. M

    : If someone was burning your head with a energy directed device?

    : If someone was burning your head with a energy directed device? Say they were very rich and performing a mean prank and burning your head causing itching and hair fall out what types of devices could be used assuming they had millions to spend.
  27. T

    Understanding head and NPSH in pumps

    So I know that head is related to energy. And it is just another way to measure the energy at any given point in the flow (although in units of meters/feet/etc). So does that mean the head is equal at all points of a pipe? Since by conservation of energy and mass, and assuming the flow is...
  28. E

    How to Calculate Flow Rate from Head Loss in a 3 Pipe with Caustic Soda?

    I have head loss (25.95ft) and converted that to pressure (17.19psi). I am trying to find flow rate in 3" sch 80 pipe coming from railcar at 25psi. So outlet pressure is 7.813psi. The fluid is 50% Caustic soda.
  29. K

    Hydroelectric Power: How Much Water for a 30m Head?

    Homework Statement Assuming 100% efficient energy conversion, how much water stored behind a hydroelectric plant with a head of 30m would be required to charge the battery? Homework Equations ? MAYBE: w=1000QgH j\s, where Q is the discharge rate @ m^3\s, 1000Q kg\s, H = net water head...
  30. N

    A bad joke or over my head?

    Just happened to see this joke in the news paper (tabloid) today. Weather has gone from +10 to -23 (windchill) in a matter of two days. That said, do dogs lay eggs when it's cold out. :rolleyes: (there is no news/politics context that I know of)
  31. J

    I cant imagine the expanding universe in my head

    Okay, so people say the universe is expanding like a 3 dimensional balloon. Now in the 2 dimensional balloon representation, it is curved so you will eventually end up in the same spot if you went in a "straight line" across its surface, like a planet. People also say that the universe most...
  32. S

    Concept of Pressure head and velocity head

    I am rather confused regarding the exact definitions of pressure head and velocity head. wikipedia defines pressure head as "a term used in fluid mechanics to represent the internal energy of a fluid due to the pressure exerted on its container. " But how can pressure head represent energy...
  33. B

    Magnitude and direction of Vectors using head to tail rule

    Homework Statement Homework Equations F = \sqrt{F_x^2 + F_y^2} tan\theta = F_y / F_x The Attempt at a Solution Page 1 : http://i49.tinypic.com/vfw74k.jpg Page 2 : http://i50.tinypic.com/2qspamr.jpg Page 3 : http://i49.tinypic.com/24zgl6x.jpg is it correct?
  34. B

    Can't wrap my head around conditional probability

    So,I'm studying statistics (for engineers) now,and this is one of them courses that really gives me a headache time after time. Here for example,I can't seem to get the difference between P(A\bigcapB),and P(A|B).I'l give an example in for of a question given to us in some class. "70 percent...
  35. L

    Wrapping my head around holography

    Having trouble wrapping my head around holography after watching/reading a ton of stuff on the topic. What I think I have found to be true is that real holograms are 3D images captured onto film that are able to be viewed at any angle through the naked eye. So the concept of a 3d image or...
  36. I

    Find the velocity of two carts after a head on elastic collision.

    Homework Statement Two carts of equal mass (15 Kg) have a head on elastic collision. The first cart has a velocity of 18.5 m/s to the right, and the second has a velocity of 12 m/s to the left. What are the velocities of the two carts after the collision? Homework Equations Since it is...
  37. F

    Gravitational head against an adverse pressure drop

    Hey, Currently I have a system where I have a high pressure at the lowest point of a vertical pipe and a low pressure at the highest point of the pipe. I want the flow to travel down the pipe vertically under gravity but I am unsure of how gravitational head works in the mechanical energy...
  38. E

    How Do You Convert mm of Head into Pascals for Aerodynamics Testing?

    Referenced pitot pressure = 107 (mm) referenced static pressure = 525 (mm)... find referenced dynamic pressure by subtracting static pressure from pitot pressure and converting to Pascals... how on Earth do you convert it to pascals?
  39. Z

    Can head loss be added in parallel like resistors in circuits?

    Homework Statement I have three valve/coil systems connected in parallel as shown in the attached figure. If I know the head loss of each valve/coil is 40 feet, can I add them in parallel like you do with resistors in circuits? Thanks! Homework Equations 1/h=1/h1+1/h2+1/h3 (possibly)...
  40. B

    Medical What is the typical tolerance of human dura mater to impact force?

    Hello world. I am in the process of writing my first true college essay, a ten-page piece on some topic relevant to my University Physics I course, but I need a little help finding some information. Google hasn't been very helpful today, and I don't even want to think about combing our terribly...
  41. A

    What are the final velocities of two balls after an elastic head-on collision?

    Homework Statement A 2.0 kg ball is traveling east at 8.0 m/s when it has a perfectly elastic head-on collision with a 3.0 kg ball traveling west at 10.0 m/s. What are the final velocities of the two balls? Homework Equations http://www.nvcc.edu/home/tstantcheva/231files/G09_hw.pdf...
  42. T

    Is it better to accelerate into a head on collision?

    Naturally, one would think, the faster your going the more energy you will create and the harder you will hit. But take a deeper look. Under the basis that in a car accident, it isn't the "Crash" that kills you, but the stop (inertia). If you were to be involved in a head on collision with an...
  43. J

    Understanding Spin in Quantum Mechanics: What Does Measuring Along an Axis Mean?

    I'm currently taking a first course in quantum mechanics and we just recently introduced generalized angular momentum. Now, take the special case of a spin-1/2 particle. If i understood this correctly there are two possibilities spin up: ms = 1/2 , and spin down ms = -1/2 , this comes from...
  44. C

    Better to stay outside the Hurricane or head inside the eye?

    Homework Statement Imagine the following. You and your best friend are at sea on your ship. Your ship is designed to withstand seas during 120 knot winds. You measure the winds outside your ship at 30 knots. From satellite images and Global Positioning System (GPS) data, you pinpoint your...
  45. T

    Head Loss in Pipe - Roughness, Velocity, Length

    Water flows through a horizontal 150 mm diameter pipe with a mean velocity of 2.5m/s. The surface roughness of the pipe is 0.15mm. Determine the head loss in a 30m length of the pipe. Hints, use moody chart, Re = ρVD/μ. Been having trouble with the question, can't seem to do it.
  46. C

    Calculating Force on Dog's Head in Collision

    I am involved in a dispute related to the forces that a dog's head is exposed to when he, of its own power, runs into a stationary object. Because of the dog's structure (this is a small dog) the head is getting pinched between the stationary object and his own back part of the body (which we...
  47. N

    Find vector whose tail & head are midpoints of

    Homework Statement Find the components of the vector v whose tail and head are the midpoints of segments AC and BC. A = (1,0,1). B = (1,1,0), & C = (0,1,1) The Attempt at a Solution I don't know what the question is asking about exactly? I find the wording very awkward.
  48. H

    Vehicle head light automation in automobiles

    Homework Statement Hi, I'm hari. I'm doing final yr B.E. I'm trying to do the headlight automation in automobiles. bt i dono by which device i can do it efficiently?? in my project i wan to sense the light and if the amount of light exceeds the particular value the vehicle wants to dim the...
  49. A

    Are Polaroid headlights the solution to reducing night-time road accidents?

    I have studied,as one of the uses of polaroids is, that it can be fitted in the head lights of cars and other vehicles to eliminate the glare. This will certainly act as a boon to the motorists and result in considerable reduction of road accidents during the night time. I have also learned...
  50. O

    Prob(2 heads | first flip is head)

    EDIT: I think I may have solved it a few minutes after I posted. See below for proposed solution ... Homework Statement Determine \textrm{Prob}(2 \textrm{heads}|\textrm{first flip is head}) by using the formula P(B|A) = \frac{P(B \cap A)}{P(A)}. Specifically, determine what the sets A and B...
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