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.
Homework Statement
The air near a water heater in the basement of an old home is measured for carbon monoxide (CO) and found to contain 0.1% by volume CO at 22*C and 1 atm. Express the CO concentration in the basement in micro-gram/m^3 .
Homework Equations
PV=nRT
P = absolute pressure (atm); V...
Homework Statement
if a =3i-4j
find a unit vector perpendicular a
Homework Equations
Vector
The Attempt at a Solution
<a> = <3 , -4>
<n> = <x, y> : x² + y² = 1
<a>•<n> = 3x-4y = 0
y = (3/4)x
x² + (9/16)x² = 1
25x² = 16
x = -4/5, 4/5
y = -3/5, 3/5
There are two unit vectors normal...
Homework Statement
Convert 1 ##Gev## to Kelvin, and convert ##GeV^{-1}## to meters, seconds, and convert ##GeV^4## to density ##(kg/ m^3).##
Homework Equations
natural units ##c=h=k_B=1##
The Attempt at a Solution
I know to convert energy to meters, I can use
##\lambda =hc/E##, I get the...
Homework Statement
Does the line through the points (−1, −1, −2) and (1, 2, 1) intersect the unit sphere? If so, find the point(s) of intersection.
Homework EquationsThe Attempt at a Solution
do i also use r = r0 + vt but instead , use equation of sphere this time?
so it would be:
v=<2,3,3>...
Homework Statement
Evaluate the integral.
\int_{-\infty}^\infty f(2 -t) \delta(3 -t) \, dt
Homework Equations
The Unit Impulse function is defined
\hspace{18mm} \delta(0) = 0 \hspace{10mm} t \neq 0
\hspace{-15mm} \int_{-\infty}^\infty \delta(t) \, dt = 1
The Attempt at a Solution
Using...
It's been a little bit since I have studied multi-particle quantum mechanics and I am a little rusty on the notation.
Let's say I have a wave function, that consists of the tensor product of two spaces, one for each particle moving, ##|\psi_1,\psi_2>##. Each of these particles is moving in a...
Homework Statement
How am I supposed to know my unit conversions? like for example 1 pound is equal to 453.592 grams I don't know how people do it, it's like they have it all memorized in their head I can't think of a way for me to be able to memorize any of it or know it am I supposed to do...
Hello,
I am attempting to calculate unit normal and tangent vectors for a scalar field I have, Φ(x,y). For my unit normal, I simply used:
\hat{n}=\frac{\nabla \phi}{|\nabla \phi|}
However, I'm struggling with using this approach to calculate the unit tangent. I need to express it in terms of the...
Homework Statement
Is intensity related to this question? The answer is B.
Homework Equations
I^2 ∝ A^2
I=P/A,
where I is intensity, P is power, and A is area
The Attempt at a Solution
I tried using I=P/A, and after substituting, I get, A^2=E/S, which gives E=A^2 S
And then, the new wave...
Homework Statement
Calculate the approximate number of board feet (one board foot is defined as a volume of ##1 in \times 1 ft \times1 ft## of lumber that would be available in a log that has a diameter of ##34 cm## and a length of ##3 m##. Assume the log is a right cylinder and that the saw...
Dear Friends,
The stress-wave propagation speed is calculated using : sqrt (elastic modulus/density)
The unit of elastic modulus is GPa, and that of density is gram/cm^dim
Can anyone please tell me how I can convert the resulting value to m/s (meter/second)?
Regards
I'm a mechanical engineering student 1st yr . I need suggestions regarding books for basic mechanical engineering and engineering mechanics . A book with basics n proper language.
Homework Statement
Coaxial cable has double layered dielectric.
a=2mm, b=4mm, c=8mm, εr1=3, εr2=4.5, Uab=1000V
1. Calculate capacitance per unit length of a cable.
2. Calculate inner and outer charge densities of a cable.
2. Homework Equations
Gauss law
C'=Q'/U
σ = nD
σp = nP
3. The Attempt...
Homework Statement
Two cylindrical conductors, of distance between them d and radius a (a<<d), have dielectric layer of relative permitivitty εr and thickness a. Calculate capacitance per unit length of this system.
Homework Equations
Capacitance per unit length, C'=Q'/U
Gauss law, cylindrical...
I'm reading a paper on a simulation of graphene and carbon nanotube growth on SiC, in the paper they give a few computational details about the structural optimization of the SiC model using a conjugate gradient method and they state the maximal force component as
1x10^{-4}Ha/a_o
What is this...
Homework Statement
From Kleppner and Kolenkow Chapter 1 (Just checking to see if I'm right)
Given vector A=<3, 4, -4>
a) Find a unit vector B that lies in the x-y plane and is perpendicular to A.
b) Find a unit vector C that is perpendicular to both A and B.
c)Show that A is perpendicular to...
Dear PF Forum,
I have a problem concerning the unit of acceleration.
All this time in Relativity, we have been talking about c.
Either as a distance unit (light travel for 1 second) or as speed.
Sometimes we describe it as 300,000. Sometimes as 300,000,000 or 186,000.
The time unit is always...
I get the dynamics of what the question is asking. What I don't get is how to know what pi/8 is. What I've been doing this entire time is plugging it into the calculator as a fraction, and getting the decimal value of it and comparing it to other values I know.
I know that pi radians = 180...
Hi,
I am a bit confused about the units of MI...I read that MI of rectangle is b*d^3/12,so unit is mm^4..Also i read in wiki that unit of MI is kg.mm^2...
Both are correct,but why this difference is?
Hi all,
In quantum mechanics, we consider the squared modulo of a wave function has meaning of probability, so does it mean a wave packet should be unitless? I am reading some materials online about the Gaussian wave packet...
Sorry if this was addressed in another thread, but I couldn't find a discussion of it in a preliminary search. If it is discussed elsewhere, I'll appreciate being directed to it.
Okay, well here's my question. If I take the divergence of the unit radial vector field, I get the result:
\vec...
Hi ALL
i need to unit Conversion :
from: 28.8 Volts/(Meter/Second) to (....) Volts/(Inch/Second)
from: 28.8 Volts/(Meter/Second) to (....) milliVolts/(milliMeter/Second)
Thanks
What's j2 in this problem?
1. Homework Statement
Homework Equations
The Attempt at a Solution
a. What's j2 in this problem?
b. How did we use the fact that we have a unit impulse?
c. What are our first thoughts and strategies when seeing the problem ?
What is our strategy? It looks...
http://tutorial.math.lamar.edu/Classes/CalcIII/CurlDivergence.aspx
In the above link, in the 2nd to last blue box on the page (where it tells how to solve a line integral with respect to a vector field using the curl), it says that the line integral of vector field F with respect to r (with an...
Homework Statement
Consider the following hypothetical question:
(5 lbs•m^2) =a
(5 rad/s^2) =b
If (a) and (b) are each multiplied by 2 what do the units become?
Similarly if (a) and (b) are squared what do the units become ?
Hi guys,
My first time here. Looks like a nice forum with friendly members.
I have a question. I'm kinda confused by this (and I know it's a shame since I'm on my third year University, almost making my degree).
What I remember from my kinematics/dynamics classes this (or similar) equation...
Homework Statement
I am having difficulty understanding the very first step of the following solved problem (I understand the rest of the solution).
How did they obtain the expressions for ##\hat{n}## (the direction of polarization), and ##\hat{k}## (the unit vector pointing in the direction...
Hello every one i have question what is the unit vector of time component like c^2 t^2 -x^2-y^2-z^2 = 0
OR
if we need to calculate the d'alembert cross some 4 vector have 3 space component x y z and unit vector i j k
and ct component what is the unit vector in Ct direction ?
Hi
I'm converting some numbers to atomic units, and it's important that I get it right. Would be happy if someone could reassure me.
I want to convert the units of an electric field measured in kV/cm to atomic units. Here is what I got:
\frac{kV}{cm}=\frac{10^3}{10^{-2}}\frac{J}{C\cdot...
The Ford Model T, affectionately known as the Tin Lizzie, is thought to have been the first widely affordable/accessible automobile. Production of the Model T started in 1908.
I'm looking for a cosmo-friendly time unit that is short enough to be real and familiar to all of us, but at least an...
1- Let the linear operator on R^2 have the following matrix:A = 1 0
-1 3
What is the area of the figure that results from applying this transformation to the unit square?
2- I am abit confused here, I thought that the matrix for the unit square would be,
0 0
1 0
0 1
1 1...
But...
Hello everyone
I have a question regarding radians and the unit of rotational energy (which has been probably asked several times elsewhere but is still confusing for me :-) ).
As I understand radian (rad) is a UNIT that is dimensionless (thus cannot be omitted), correct ?
Now if I want to...
Homework Statement
Find a unit normal to the plane containing a and b. a=(3;-1; 2) and b=(1; 3;-2)
Homework Equations
\frac{V}{|V|} where V = a+b
The Attempt at a Solution
(3;-1; 2) +1; 3;-2)=(4,2,0)=V
|V| = \sqrt{4^2+2^} = 2\sqrt{5}
there fore the unit vector is (\frac{2}{\sqrt{5}}...
Is there an error, perhaps typographical, in the famous 1939 Oppenheimer-Snyder paper "On Continued Gravitational Contraction" (Phys Rev v56 Sept 1, 1956 pp 455-459)?
Do the units balance in equation 37? The last term inside the last parantheses
##\frac{3r_0^{1/2} \tau}{2R_b^2}##
where...
Homework Statement
For f(x,y)=x^2-xy+y^2 and the vector u=i+j.
ii)Find two unit vectors such D_vf=0
Homework Equations
N/A.
The Attempt at a Solution
Not sure if relevant but the previous questions were asking for the unit vector u - which I got \hat{u}=\frac{1}{\sqrt{2}}(i+j) for the maximum...
Hi, I was wondering if anyone could help with a vector question that I have.
If I have a unit vector defined in cartesian co-ordinates as p= (0,1,0) how would I go about converting this vector to a cylindrical geometry.
I understand that I will probably need to use p_r=sqrt(px^2+py^2) and...
Homework Statement
An Indy 500 race car's velocity increases from 4m/s to 36m/s over a 4 second time interval. What is its acceleration? 4m/s is the initial velocity, 36 m/s is the final velocity, and time is 4 seconds.
Homework Equations
final velocity = initial velocity + (acceleration x...
Homework Statement
A rectangular loop of wire is placed next to a straight wire, as shown above. There is a current I in both the straight wire and the loop. The dimensions shown in the figure are a, b = 2.2a, and c = 8a. What is the magnitude of the force on the loop? Express your answer in...
What is the unit value of coulomb constant(k)?
I just want to know the CGS unit value of k.
In my book it is said the CGS unit value of k is 1.
By i don't know how it come.?
Homework Statement
Homework Equations
Laplace Trasformations
The Attempt at a Solution
a. done
b. f(t)= t -3*t*u(t-1) + 4*u(t-1) -3*u(t-2) -2*t*(t-2)
c. 1/(s^2) - (3e^-s -2e^-2s)/(s^3) + (4e^-s -3e^-2s)/s
d. 1/(s-1) * (1/(s^2) - (3e^-s -2e^-2s)/(s^3) + (4e^-s -3e^-2s)/s)
These are the...
Hi
Assume an x-coordinate from the unit circle is picked from a uniform distribution.
This is the outcome of the random variable X with probability density function Xden(x) = 0.5 (-1 < x < 1).
The random variable Y is related to the random variable X by Y = f(X) = √(1-X2) and X = g(Y) =...
Hi everybody; I am triying to calculate the Bohr Magneton (eħ/2mc); I am suposed to express it in units of MeV/ Gauss, but I have not idea how to transform charge/time, which is what I obtain when I introduce the units in the formula.
Can anyone help plase?
Thanks.
solar updraft tower: How small a working unit can be made?
My reason to ask this question is:
I think that if a commercial unit is ever to be built, first the concept must be widely established.
One or two working examples of a size similar to the prototype built in Spain won't likely prove...
Hey guys, wasn't too sure where I should post this but here goes:
Im currently taking a grade 11 introductory physics course in Ontario, Canada. We are currently learning the basics of nuclear physics. For most units, I'm able to foresee the thinking (hard) questions our teachers usually point...
I'm reading Julian Barbour the end of time..I don't know if It's a good reading..
According to Planck unit of time (5.39121 × 10^−44 seconds), could the universe be said to have a "frame rate" and "snapshots" (as Julian Barbour mentions) could exist? (and, incidentally, Zeno's arrow paradox...