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.

View More On Wikipedia.org
1. change in the unit vectors

i tried integrating the stuff but it didn't work what to do
2. What is the Equivalent Strength of the Chicxulub Impact in Atomic Bombs?

Hi PF Forum, How are you guys. I hope you guys are doing fine. I often come a statement like this. This earthquake is as strong as 1 million atomic bombs. This volcano is as strong as some million atomic bombs. And now in this video. Chicxulub impact "... this impact carried more than 10...
3. How do I calculate the rate constant units for excitation by electron impact?

Hi, I struggle to calculate the unit of the rate constant that is [m^3/sec] rate constant of excitation by electron impact is as follows: where, e=charge of electron [Coulomb], me=mass of electron [kg], ε=energy [eV], σe(ε)=cross section for electron impact [m^2], f(ε)=electron energy...
4. Conventional current definition and a variation on that definition

One normally sees that the definition for conventional current as defined as the amount of positive charge that passes a point over unit time. However, why could we not define conventional current as the amount of positive unit charge that passes a point over unit time. I added in unit there...
5. I Questions Regarding Primitive Unit Cell

Questions regarding Primitive Unit Cell (and what I think the answer are, correct me if I am wrong) 1. Can there be more than one Primitive Unit cells for the same crystal? yes, Wigner Seitz cell always will exist. There can be other primitive Unit cells along with Wigner Seitz too. But...
6. Condensate flow and mold in mini-split ductless AC indoor unit

My AC has begun to emit a rather foul smell, which has led me to geek out on the inner workings of its indoor section. For example, how does the condensed moisture make its way to the drain pan? I am assuming that the condensation happens on the fins of the evaporator. But in that case, what...
7. A Finding Minimal Mean Distance Curves on the Unit Sphere

**Problem:** Find parametric equations for a simple closed curve of length 4π on the unit sphere which minimizes the mean spherical distance from the curve to the sphere; the solution must include proof of minimization. Can you solve this problem with arbitrary L > 2π instead of 4π? There...
8. Power factor of a retrofitted LED unit in a fluorescent fitting

A poster on another forum has fitted a large number of 230V 50Hz 24W nominal LED tubes, apparently designed to be plugged straight into the old fluorescent fittings. He has found, by clamp meter measurement, that the new LED lights appear to be consuming 80W, not the claimed 24W. A number of...
9. Three Phase Per Unit System - Mark up, represent as single phase equiv

I'm seeking some reassurance I've understood the question since there are no answers given in the book and I'm getting a bit tied up in knots. What I am struggling with most is there are three per unit values for impedance already noted on the diagram without qualifying what ##Z{base}## is or...
10. POTW Fourier Series on the Unit Interval

Evaluate the Fourier series $$\frac{1}{\pi^2}\sum_{k = 1}^\infty \frac{\cos 2\pi kx}{k^2}$$ for ##0 \le x \le 1##.
11. I Law of Cosines in Linear Algebra: Understanding the Dot Product of Unit Vectors

HI, I am studying linear algebra, and I just can't understand why "Unit vectors u and U at angle θ have u multiplied by U=cosθ Why is it like that? Thanks
12. I Orbital Precession Calculation: Unit Explained

Hi, I've just calculated the orbital precession for the earth using the sigma formula of general relativity. $$\sigma=\frac{24 \pi^{3} R^{2}}{T^{2} c^{2}\left(1-e^{2}\right)}=\frac{24\pi^3×1.5×10^{11}}{3×10^7×3×10^8(1-0.0034^2)}=0.012$$ What is the unit of the result? Degrees per century or...
13. How to Determine the Unit Cell Type From the XRD Data?

Hey guys, I got an XRD data for my sample and want to determine its density. This requires finding lattice parameters. However, I'm not certain about the crystallographic system of my sample. How can I determine the type of the unit cell my sample has from XRD data (I can use GSAS II if...
14. How Do You Convert Seconds to Nanoseconds in Scientific Notation?

How do you convert ##1.66 \times 10^{-7} s ## to ##ns##? I know the answer is ##166 ns = 160 \times 10^{-9} s## however what is the thought process? Many thanks!
15. B Calculate Unit Normal Vector for Metric Tensor

How do I calculate the unit normal vector for any metric tensor?
16. What is the smallest unit of measurement used that the eye can see?

There are units of measurement smaller than our eyes can see, but that we use in science. But, what is the smallest one that we can see and work with regularly? I mean...on a traditional ruler, it'd be a millimeter, right? But, we can obviously go smaller - even if a ruler doesn't mark it...
17. A Underwater acoustic unit conversion

Hi all I have acoustic noise level value in dB vs 1 dyne/sq cm e.g. -10 db vs 1 dyne / sq cm. I need to convert it into dB ref 1upa unit. How i will convert it? Thanks & Regards
18. Useful Cooking Unit Conversion

A hollow rectangular tube with cross-sectional area of 1 barn and a length of 1 megaparsec will hold a quantity of material of approximately 2/3 of a teaspoon.
19. Coloring each k-th unit in a circle of n units

suppose you write, clockwise, n numbers (or "units", doesn't matter) in a circle. you then color, clockwise, each k-th number. you do this until you've colored all n numbers, or until you've reached an already colored number. let x be the number of colored numbers. i've figured that if...
20. I Converting density unit ##MeV^4## to SI units

How to transform density unit in natural units $MeV^4$ to SI units $kg/m^3$, Here's my trial: ##MeV^4 = (10^6)^4 ~ eV^4 = 10^{24} ~ eV^4 ##, ## eV = 1.6 * 10^{-19}~ kg~ m^2 / sec^2, ## ##MeV^4 = 10^{24} ~ 1.6^4 * 10^{-40} ~ kg^4 m^8 / sec^8 ## This is not simply ##kg/m^3##! Any help how to...
21. MHB Forward Unit Push Operator Equation

Hopefully the symbols I am using are standard. I will define them upon request. I have a theorem that says, given a difference equation \left ( \sum_{j = 0}^m a_j E^j \right ) y_n = \alpha ^n F(n), we can define a polynomial function \phi (E) = \sum_{j = 0}^m a_j E^j such that \phi (E) y_n =...
22. I Trouble understanding the SI definition of 1 second

Homework Statement:: The SI definition of unit of time says the following. "The second is the duration of 9192631770 periods of the radiation corresponding to the transition between the two hyperfine levels of the ground state of the caesium 133 atom." Relevant Equations:: None I know an...
23. Insights A Novel Technique of Calculating Unit Hypercube Integrals

Introduction Best viewed on a desktop, if you must use a phone, maximize your browser in landscape mode and sorry some of the math won’t fully display on a mobile yet. In this insight article, we will build all the machinery necessary to evaluate unit hypercube integrals by a novel technique...
24. Vector problem: Questions about a unit vector

Not sure how to show that because ##\vec{v} = |v|\hat{v} = 3|e|\hat{e}##, but since ##\vec{e}## is a unit vector we know ##|e| = 1## so our equation now becomes ##\hat{v} = \frac{3\hat{e}}{|v|}##. So, we're left to the task of showing that ##|v| = 3## in order to conclude that ##\hat{v} =...
25. Determine the unit tangent vector

I need a justification that ##|\dfrac {dr}{dt}|##=##\dfrac {ds}{dt}## cheers guys... all the other steps are easy and clear to me...
26. Determine a unit vector perpendicular to the given planes

I looked at this question and i wanted to ask if we could also use; ##C## =## c_2 ##(##-\dfrac {3}{2}i## +## j - 3k)## ... cheers This problem can also be solved by using the approach of cross product ##A×B##...
27. One-parameter parametrization of a unit circle in R^n

I tried to looking at lower-dimensional cases: For ##n=2## we have $$(x(t),y(t))=(cos(t),sin(t))$$ For ##n=3## we define two orthogonal unit vectors ##\vec{a}## and ##\vec{b}## that are orthogonal to ##\vec{u}##, leading to $$(x(t),y(t),z(t))=(cos(t)(a_1,a_2,a_3)+sin(t)(b_1,b_2,b_3))$$ It seems...
28. How is the current density solved for in an electrolyzer unit?

Hydrogen production rate is typically measured in current density, but what is the area in which the current is divided by to find such a value?

30. Unit Basis Components of a Vector in Tensorial Expressions?

Divergence formula $$\vec{\nabla} \cdot \vec{A}= \frac{1}{\sqrt{G}} \frac{\partial}{\partial q^{j}} (A^{j} \sqrt{G})$$ If we express it in terms of the components of ##\vec{A}## in unit basis using $$A^{*j} = \sqrt{g^{jj}} A^{j}$$ , we get \vec{\nabla} \cdot \vec{A}= \frac{1}{\sqrt{G}}...
31. Help with unit vector for a magnetic field

So when evaluation the cross product of the velocity of the charge and the unit vectors associated with the point I am getting v x r = j x [ i + j]. Well j x j is 0. j x i = -k, but yet the answer is positive. Why is this?
32. Biomass gasification unit vs biomass combustion unit

Good morning to all of you. For my diploma thesis I have to compare the combined production of electricity and heat from a biomass gasification unit and from a biomass combustion unit. So I would like to ask you if you know data or refer me to papers so that I can compare these 2 technologies...
33. I Equation to graph a sine wave that acts like a point on a unit circle

I need an equation to graph a sine wave that act like a unit circle but only positive numbers. so I need it to be 0 at 0, A at 90 , 0 at 180, A at 270, 0 at 360, and A at 450 and so on and so on... Now I know sin(0) is 0 in degrees and sin(90) 1 and I know if you Square a number is...
34. Need a force-like unit for classical particle system simulation

I am doing a learning project by writing a simulation that includes capacitance and current flow amongst capacitors that may potentially be in parallel. I don't care about certain details yet - dissipation factor, frequency dependent effects, temperature. Tiny capacitences within diode junctions...
35. Displacement problem with unit vectors

(a) I did (7.07*4.1)-(-7.03*3.94)=56.7 with this method I got this answer correct in my first attempt. (b) This where I seem to have gone wrong. I used a · b = (axbx +ayby) then I used a = sqrt(ax2+ay2) to get a single number for the answer. Filling in the numbers 7.07*-7.03 + 4.94*4.1 =...
36. B Problem involving unit vectors

For example is this correct : 19icap.4(-i cap) = 76(i.-i)= 76 Or is it , take - out. Then -76(icap.icap)= -76 Is it -76 or 76 ?
37. Understanding Direction of Unit Vectors r roof & phi roof

The unit vector r roof points in the direction of increasing r with phi fixed; phi roof points in the direction of increasing phi with r fixed. Unlike x roof, the vectors r roof and phi roof change as the position vector r moves. What I was thinking of the image is Although, I was thinking why...
38. I General Method for Mapping an Ellipsoid to Unit Sphere

I have been working on a problem for a while and my progress has slowed enough I figured I'd try reaching out for some more experience. I am trying to map a point on an ellipsoid to its corresponding point on a sphere of arbitrary size centered at the origin. I would like to be able to shift any...
39. I Unit Norm Axis Rotation in R3: Exploring Representation & Algebra

Now, i am extremelly confused about all this thing. More preciselly, i can't understand how 1.29 was obtained. It was used the A representation? How do he uses it? There is something to do with the canonical basis?
40. Unit calculations - DWI MRI (Stejskal-Tanner)

Ok, so basically my task is to calculate the apparent diffusion D based on experimental data, which is kind of easy, BUT the problem is with unit of b... Gamma is gyromagnetic ratio and can be expressed as: (s*T)-1 or MHz/T --> but I am not so sure, teacher did not specify Delta is the pulse...
41. Unit vectors -- How can they be dimensionless?

Hi, what is a unit vector? I mean, it is ##\hat{A}=\vec A/|A|##. A dimensionless vector with modulus (absolute value) one, I've read somewhere. So, dimensionless with modulus. Isn't that a contradiction? I mean, absolute value regardless dimension? Am I out of context?. ##\Bbb R^3## is a...
42. I How to ensure an equation is dimensionless when it includes "Debye"

I am trying to check if an expression is dimensionless. If it is, then I have done things correctly. However, I am stuck on how to deal with a (Debye^2) term. How can I break it down to find out if it cancels out with the other units I have left? I know this is probably a trivial question...
43. Digital Filters: why is sampling frequency equal to 2*pi unit circle

Hi, I was working through a filter design problem and got stuck on a concept. Scenario: Let us say we have the following pulse transfer function and the sampling frequency is ## f_s = 50 \text{Hz} ##. G(z) = \frac{1}{3} \left( 1 + z^{-1} + z^{-2} \right) The zeros of the transfer function...
44. Is there a smooth function in the unit ball with compact support?

Is there a function that takes positive values only in the unit ball not including the boundary points defined by the set ##\{x^2+y^2+z^2<1\}##, and ##0## everywhere else?
45. MHB Draw Angles & Find Values in Unit Circle

Hey! :giggle: Make a drawing for each of the values of the angle below indicating the angle at the unit circle (in other words: $\text{exp} (i \phi )$) and its sine, show cosine, tangent and cotangent. Give these four values explicitly in every case (you are allowed to use elementary...
46. MHB M has the unit matrix at the upper left side and zero everywhere else

Hey! :giggle: Let $\lambda\in \mathbb{R}$ and \begin{equation*}a=\begin{pmatrix}1 & 2 &-1& \lambda & -\lambda \\ 0 & 1 & -1& \lambda & 2\\ 2 & 2 & 1 & 1 & 3\lambda-1 \\ 1 & 1 & 1 & \lambda & 5\end{pmatrix}\in \mathbb{R}^{4\times 5}\end{equation*} (a) Let $\lambda=1$. Determine a Basis...
47. Molarity is represented by M and its unit is also M?

In my textbook it is given that Molarity is represented by M, and its formula is-- Molarity(M)= No. of moles of solute/Volume of solution in L the unit of Molarity is mol/l which is also written as M. Now what does this mean ? does it mean --> Molarity is denoted by "M" and it's unit is also...
48. Engineering Should the # of atoms in a unit cell be considered to find the % volume change?

First of all, I don't think the question was clear enough. Therefore, I had to assume they are referring to the volume of the unit cell. V=a^3, side length a aBCC=2R√2, aFCC=4√3/3R %change=(VFCC-VBCC)/VBCC I thought this was right until I checked with others who did this: so the only...
49. What is the definition of Unit Optical Depth?

$$\chi = n \sigma$$ Where Chi is the Opacity, n is the number density of absorbers (constant), and $\sigma$ is the cross section(given). We define the optical depth is just the number of photon mean-free paths in a given physical step, i.e. if we consider a...
50. I Riemann Curvature Tensor on 2D Sphere: Surprising Results

I have worked out (and then verified against some sources) that ##R^\theta_{\phi\theta\phi} = sin^2(\theta)##. The rest of the components are either zero or the same as ##R^\theta_{\phi\theta\phi} ## some with the sign flipped. I was surprised at this, because it implies that the curvature...