Unit Definition and 1000 Threads

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...

if acceleration is defined as rate of change in velocity, then how do you find out the unit of rate of change of acceleration?

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...

I was going through this link -...

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...

Flux is the no. Of electric field lines per unit area..how can it have a unit

Just simple questions and I need clarifications why is that your answer please. 1,602 ×10^−19 C write to SI Unit Prefixes

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...

Homework Statement Given the relationships: Xpu = MVAbase / MVAfault Xpu = ( MVAbase / MVArated ) * ( X% / 100 ) MVAfault = sqrt(3) * V * Ifault Xohms = [ V / sqrt(3) ] * Ifault Homework Equations Show that: Xpu = [ MVAbase / V^2 ] * Xohms The Attempt at a Solution No matter how I...

Hello! I need help with this problem how do you find a unit vector along the direction $\vec{A}=2\hat{a_{\rho}}-z\hat{a_{z}}$(cylindrical)? do I have to convert it to Cartesian or there is a direct method? please help! Thanks!

Homework Statement [/B] This problem is from Jon Rogawski's Calculus-Early Transcendentals At a certain moment, a moving particle has velocity v={2,2,-1} and a={0,4,3}. Find T, N and the decomposition of a into tangential and normal components.Homework Equations ANYTHING IN [ ] REPRESENTS A...

Homework Statement y(t) = e^{a(t-t_{0})} y(t_{0}) + \int_{t_{0}}^{t} e^{a(t-\tau)}b \dot{u} (\tau) d\tau u(t) = \delta(t) = \frac{1}{2} c^{3} t^{2} e^{-ct} where c >> |a|, t_0 = 0, and y(0) = 0 Find y(t) and represent the unit impulse, delta, in the solution. The remaining terms should not...

Write the piecewise function \[ f(t) = \begin{cases} 2t, & 0\leq t < 3 \\ 6, & 3 \le t < 5 \\ 2t, & t \ge 5 \\ \end{cases} \] in terms of unit step functions. So here is what i;ve got just guessing , I don't think I'm correct. I really need some help. But I got...

MODERATOR NOTE: THERE IS NO TEMPLATE BECAUSE THIS THREAD WAS ORIGINALLY MISPLACED IN A NON-HOMEWORK FORUM Viscous liquid (ρ = 1460 kg/m3, μ = 5.2×10−1Ns/m2) is pumped through a smooth pipe with a 0.1 m diameter, at a rate of 5×10−2m3/s. Using your Fanning friction factor versus Reynolds Number...