What is Unit: Definition and 1000 Discussions

UNIT is a fictional military organisation from the British science fiction television series Doctor Who and its spin-off series Torchwood and The Sarah Jane Adventures. Operating under the auspices of the United Nations and initially led by Brigadier Lethbridge-Stewart, its purpose is to investigate and combat paranormal and extraterrestrial threats to Earth. Several UNIT personnel (such as the Brigadier, Sergeant Benton and Mike Yates) played a major role in the original Doctor Who series, and it was a regular feature from The Invasion (1968) until The Seeds of Doom (1976).
Originally referred to as the United Nations Intelligence Taskforce, executive producer Russell T Davies said in 2005 that the UN was no longer happy to be associated with the fictional organisation and the UN's full name could now no longer be used. However, the "UNIT" and "UN" abbreviations could be used as long as it was not explained what the letters stood for. In 2008, he announced that the organisation's name had been changed to the Unified Intelligence Taskforce. This new name was first mentioned on-screen in "The Sontaran Stratagem", also in 2008, in which it was indicated in a line of dialogue that the United Nations still supports UNIT with funding.

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  1. D

    Thermodynamics - Work done per unit mass

    Homework Statement A sample of dry air has initial pressure p1 = 1000 hPa and temperature T1 = 300k. It undergoes a process that takes it to a new pressure p2 = 500 hPa with unchanged temperature T2 = T1. Compute the mechanical work per unit mass performed by the sample under the following...
  2. T

    Calculating the Mass of an Aluminum Unit Cell

    Aluminum has a density of 2.699 g/cm3 , and the atoms are packed in a face-centered cubic crystal lattice. Find the mass of a unit cell. -----I already know the answer is 1.792*10^-22g/unit cell I have a question about how you get the answer: I know you multiply 4.480*10^-23g * 4 atoms/1...
  3. B

    Unit conversion inside a derived gausses law eq

    Homework Statement Essentially I'm working out a problem and I am given \alpha = \frac{15cm\bullet m^{3}}{\mu C} and I need to get it in just terms of meters/coulombs I'm having a real tough time with weird unit conversions like this. Homework Equations 1m = 100cm 1 micro coulomb = 1 X...
  4. N

    How to transform Ry unit of Energy to Hartree?

    How to transform Ry unit of Energy to Hartree?? Hi How to transform Ry unit of Energy to Hartree??
  5. P

    Linear Algebra unit vectors

    Three unit vectors v1 v2 and v3 are in R^n. We are told that v1 dot v2= v1 dot v3=1/2. What are the possible values of v2 dot v3. What could the angle be between the vectors v2 and v3 give example for the cases in R^2 and R^3. costheta = (x dot y)/((magnitude of x)(magnitude of y) I...
  6. B

    Physics Grade 12 HELP Electricity Unit

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  7. G

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  8. S

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  9. T

    Signals & Comms: Unit step function - dirac

    Homework Statement The Dirac function (unit impulse) is defined as \delta(t) = 0 where t \neq 0 the integration of d(t) between -ve inf and +ve inf is 1. Now I picture this as a rectangle with no width and infinite height. In fact I think of the width (along the x axis) as (1/inf =...
  10. J

    What is the correct unit this volume equation?

    If a cubic box(all sides the same length) has a volume of 1.0 L, what is the length of each side of the box? (L= Liter) V= l x w x h or in the problem V=s^2 So I did: 1.0 L^(1\3) = s^3(^1\3) so I got each side to = .33 What I am confused about is what unit is normally...
  11. J

    What is the meaning of luminosity per unit frequency?

    I am just trying to understand exactly what luminosity per unit frequency is. I know that luminosity (L = 4PI(r2)(flux)) is amount of energy per unit time, but not sure what it means when it is also per unit frequency. The question has a cosmic source of 100 solar luminosity, all emitted...
  12. D

    DE: Unit Cancellations Not Making sense

    Homework Statement Consider a tank used in certain hydrodynamic experiments. After one experiment the tank contains 200 liters of a dye solution with a concentration of 1 g/liter. To prepare for the next experiment, the tank is to be rinsed with fresh water flowing in at a rate of 2...
  13. M

    How can I find a unit vector that bisects the angle between two given vectors?

    Here's the problem I've been having difficulty with: Find a vector with a magnitude of 1.00 that bisects the angle between the vectors 5.00i + 11.0j and 2.00i − 1.00j. Give your answer in rectangular coordinates. Someone else had posted this same question before, but the answer that was...
  14. Useful nucleus

    An easy way to generate the unit cell

    If I have the fractional coordinates of asymmetric unit and I know the space group of certain material, is there an easy way to generate the fractional coordinates of the atoms in the conventional unit cell?
  15. R

    Integral form of the unit step function

    Homework Statement I need to show that the unit step function (\Theta(s) = 0 for s<0, 1 for s>0) can be written as \Theta(s)=\frac{1}{2\pi i} \int_{-\infty}^{\infty} dx \frac{e^{ixs}}{x-i0}. Homework Equations - The Attempt at a Solution Firstly, I'm unsure about what "x-i0" actually...
  16. T

    How to Calculate a Unit Vector Perpendicular to a Plane?

    Homework Statement Given that a = (-1,16,-1) and b = (-18,-15,-15), find the unit vector which is perpendicular to the plane containing a and b. There are two possible answers. Choose the answer with a positive x component. Homework Equations (a*b) = (a2*b3-a3*b2)i -...
  17. T

    Problem with vectors and unit vectors

    Homework Statement An electric charge e which moves through a material of permeability μ with a velocity v, produces a magnetic field β at a point r given by: β= ((μ*e)/(4*∏))*((v*ru)/(|r|)2) where ru is a unit vector in the direction of r. Find β if v=4i+3j+3k and r=4i+7j+5k. Take...
  18. S

    Polar Unit Vectors: Defining in Relation to Cartesian System?

    Can polar co-ordinate system only be defined in a "background" Cartesian co-ordinate system? What I'm confused about is this: the definition of the polar unit vectors or the polar basis is in terms of the parameter theta. Now, before we go about defining our basis we need to define this theta...
  19. H

    Unit Vector of f(x) at point

    Homework Statement Find a unit vector (a) parallel to and (b) normal to the graph of f(x) at the given point. Then sketch a graph of the vectors and the functions. Function: f(x)=xx Point: (3,9)Homework Equations The Attempt at a Solution...
  20. R

    Unit translation vectors, bcc structure

    Homework Statement Can someone please try to help me with this. I have a bcc structure and the question is ''Clearly indicate the unit translation vectors and state their value in Å. I have attached the sketch : http://img440.imageshack.us/img440/4879/picture3lh.jpg are those t1,t2,t3...
  21. M

    Unit Circle: 360 Degrees = 2(pi) Radians

    The book talks about a unit circle... 360 deg = 2(pi) rad if it wasnt a unit circle... say r = 4 would it then be 360 deg = 8(pi) rad?
  22. R

    Show that M(z) maps the unit circle to itself.

    Homework Statement consider the family of complex mappings: z -> Ma(z) = (z-a)/(áz-1) (a constant) (á is complex conjugate of a) Show that Ma(z) maps the unit circle to itself.Homework Equations the solution should look something like this i guess: Ma(ei*alpha) = ei*alpha The Attempt at a...
  23. A

    Thermodynamics question about mass flow rate in an air conditioning unit?

    1. In an air conditioning unit fresh air at 10°C is mixed with warm air at 30°C. If the mass flowrate ratio of warm to fresh air is 1.6, estimate the temperature at which the mixed air leaves the air conditioner. State any assumptions made. and also do you always make the air standard...
  24. C

    How can I find a unit vector that bisects the angle between two other vectors?

    Find a vector with magnitude of 1.00 that bisects the angle between the vectors 5.00i + 11.0j and 2.00i - 1.00j. Give your answer in rectangular coordinates. I'm not going to lie, I am terrible at physics and I had no idea how to solve this question, so I asked someone for help. I came out...
  25. C

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    Homework Statement r(t)=ti+t^2j Find the velocity, speed, acceleration, unit tangent, and unit normal vectors.Homework Equations Velocity=r'(t) Speed=magnitude of r'(t) Acceleration=r''(t) Unit tangent=r'(t)/magnitude of r'(t) Unit normal=d/dt[unit tangent]/magnitude of d/dt[unit tangent]The...
  26. A

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    Homework Statement Choose a point in the unit axis, say x.Let Y be the distance of that point and the point where thε perpendicular line crosses the unit circle. Find the density and cumulative functions of Y. Homework Equations Basic trigonometry i guess. The Attempt at a Solution...
  27. C

    Unit Circle Solutions for Various Angles

    Does anyone know the (x,y) solutions on the unit circle for 15, 75, 105, 165, 195, 255, 285, or 345 degrees?
  28. K

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    H(x,y)=<x^2/4,y^2/9,xy> the region E is 9x^2+4y^2<=36 also wat is given is the work is counterclockwise on R=<2cost,3sint> from -pi<=t<=pi wat the questions are what is the unit tangent the outward normal vector with respect to the region E in terms of t. for the unit tangent i think its...
  29. P

    Help with Heaviside unit functions

    Hi, I'm not really understanding how to convert the piecewise heaviside into a single function. This was on our quiz and the professor didn't really explain how he got the answer. I can't get the tex to work so: f(t)= { 0, 0 <= t < 1 { (t-1) 1 <= 2 { 1, t >= 2 The answer is...
  30. M

    Quick calculation of lattice parameter and unit cell volume for germanium?

    Homework Statement Calculate dhkl and vc for the (111) direction of germanium. Homework Equations dhkl=a/sqrt(h2+k2+l2) vc=unit cell volume=a1dot(a2xa3) or vc=structure form factor/density The Attempt at a Solution dhkl=a/sqrt(3) I know how to solve this, I've just...
  31. D

    Find Unit Vector perpendicular to the Surface

    Find Unit Vector perpendicular to the Surface, x3+zx=1 at the point P=(1,2,-1) I figures that the perpendicular vector would be, N(X)=grad(x3+zx) = (3x2+z, 0, x) N(P)= (3,0,1) Then the unit vector would be, n=N(P)/||N(P)|| n=(3/51/2,0,1/51/2) The answer i get is not the...
  32. B

    Analyzing Kac's Random Walk - Randomly rotating unit vectors

    Homework Statement Let us define the following random walk: Start with a randomly chosen (with uniform probability) unit vector (with respect to the usual Euclidean norm) in \mathbb{R}^n and call it x^{(0)}. Now, x^{(t+1)} is generated from x^{(t)} in the following manner - randomly and...
  33. A

    Exploring the Scalar Gradient and Unit Vectors

    greetings in a scalar gradient why does the unit vector has appeared?scalar gradient only represent the change in that scalar quantity along x,y and z axis.then why unit vector along x, y and z comes in picture? advanced thanks.
  34. S

    Unit Conversion: Solving for Speed of Water Flow

    Homework Statement water flows into a tube with a diameter of 6.35 cm at 0.012 meters cubed per sec. it exits the nozzle with a diameter of 2.2cm at what speed? Homework Equations a = pi r squared A1V1 = A2V2 The Attempt at a Solution My question is should i convert the cm to...
  35. S

    Finding the Unit Normal Vector at t=0: A Headache-Inducing Problem

    The position vector is r(t)= \sqrt{2}t\bar{i}+e^{t}\bar{j}+e^{-t}\bar{k} and it is asking for the unit normal vector at the parameter which is t=0. I have tried this problem many times and I guess it is all of the simplifying that is driving me bonkers! [b]2. I know that to find the...
  36. J

    Laplace transform with unit step function

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  37. M

    Integral domain unit problem

    Question: Show that if R is an integral domain then R^x=R[x]^x(or that the units in R[x] are precisely the units in R, but viewed as constant polynomials).
  38. V

    Torque in Unit Vector Notation

    Homework Statement Homework Equations Torque is equal to the derivative of angular momentum with respect to time The Attempt at a Solution I took the derivative of each function given in parts a - d and plugged in the value for t to get my answer for the torque. I don't quite...
  39. M

    Proof of Unit Sphere Homework Statement

    Homework Statement f is a polynomial with n variables (x1, x2, ... , xn) with real coefficients. Let Sn-1 = {x E Rn | x12 + x22 + ... + xn2 = 1} (n-1 unit sphere). Show that \exists b,c E Sn-1 such that m = f(b) \leq f(x) \leq f(c) \leq = M for all x E Sn-1. If f(x1, ... , xn) = a1x1 + a2x2...
  40. P

    Estimating dehumidification rate with A/C unit

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  41. J

    Memorizing the Unit Circle: Tips & Tricks

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  42. C

    What is the derivative of a unit step function with discontinuities at -2 and 2?

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  43. A

    Designing an Auto Match Unit for RF supply

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  44. K

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  45. C

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  46. C

    About the unit of Radial wave function R(r) of Hydrogen atom

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  47. S

    Atomic mass unit and Molar mass

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  48. L

    Question about unit conversion

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  49. C

    Writing unit vectors in terms of sin/cos?

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  50. R

    How do you parametrize the unit square in the complex plane?

    My book just gives me what each individual piece is but doesn't explain anything.
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