Position Definition and 1000 Threads

In the statement encircled, what does Griffiths actually mean?

Vertical position (x component): y(t) = y0 +v0 * t -1/2*g*t^2 Position yx(t) = 0cm = 40cm + 0 *t -1/2 * 981cm/s/s * t^2 edit: I replaced v0 = 0 and got t = 0.286s, which is incorrect according to the submission. This didn't work so I thought maybe by finding the angle of the throw would help...

Is this sentence correct? Our Sun lies in one of the spiral arms of the Milky Way, about 2/3 of the way out from the center of the galaxy.

I have a basic question regarding quantum systems in their potential and defined states: Do quantum systems exist in many possible states (i.e. defined as an uncollapsed wave function) merely because we don’t know what state it’s in (i.e. because we haven’t ‘observed’ or measured it, and...

While trying to find the expectation value of the radial distance ##r## of an electron in hydrogen atom in ground state the expression is : ##\begin{aligned}\langle r\rangle &=\langle n \ell m|r| n \ell m\rangle=\langle 100|r| 100\rangle \\ &=\int r\left|\psi_{n \ell m}(r, \theta...

I am having trouble with the spacing and positioning of some number line. Sorry for any format problems. \usepackage{tikz} \usepackage{parskip} \subsubsection{Graphing Real Numbers on Number Line} We can graph subsets of real numbers on the number line. The number lines continue forever...

Hello! So, I was beginning to skim Kleppner and Kolenkow for an upcoming course I’m taking over the summer. I saw this on pg. 17 and was wondering if I’m making a silly mistake in understanding what the book is saying. When they take the derivative of the position function, isn’t the velocity...

Will this dipole rotate or change position? The external electric field is in black. Two charges with their electric fields are drawn in orange.

Can I conceive a countable position basis in Quantum Mechanics? How can I talk about the position basis in the separable Hilbert space?

ok this is out of an old textbook and possibly already posted here so.. A movie stunt woman drops from a helicopter that is 30.0 m above the ground and moving with a constant velocity whose components are 10.0 m/s upward and 15.0 m/s horizontal and toward the south. Ignore air resistance. [a.]...

Hello there, for the above problem the wavefunctions can be shown to be: $$\psi_{n,l}=\left[ \frac {b}{2\pi l_b^2} \frac{n!}{2^l(n+l)!}\right]^{\frac12} \exp{(-il\theta - \frac {r^2\sqrt{b}}{4l_b^2})} \left( \frac {r\sqrt{b}}{l_b}\right)^lL_n^l(\frac {r^2b}{4l_b^2})$$ Here ##b = \sqrt{1 +...

We've two operators ##\hat{a}##,##\hat{b}##. I know their position representation ##\langle r|\hat{b} \mid \psi\rangle=b## ##\langle r|\hat{a}| \psi\rangle=a ## Is it generally true that the position representation of the combined operator ##\hat{a}\hat{b}## is ##a b## where ##a, b## are the...

One of the component of angular momentum operator is ##\hat{L}_{x}=\hat{y} \hat{P}_{z}-\hat{z} \hat{P}_{y}## I want it's position representation. My attempt : I'll find the representation of the first term ##\hat{y} \hat{P}_{z}##. The total representation is the sum of two terms. The...

I am very interested in quantum mechanics/physics and i keep seeing the Heisenberg uncertainty principle and its making me think about other forms of viewing particles. We traditionally use Photons to view something (our eyes), or other forms of radiation/particles, but i know that merely...

I am doing a University lab project where I measure positions of sunspots (using images from NASA's SDO) and use them to calculate the rotation of the Sun. Currently, all is going well: I have the angular velocity of several sunspots at varying heights. However, I want to be able to find the...

In the double-slit experiment with two open slits, is there a fixed relationship between the momentum (p) of the particle immediately after passing through the slit and the position (q) of the impact on the screen?

I'm trying to find the adjoint of position operator. I've done this: The eigenvalue equation of position operator is ##\hat{x}|x\rangle=x|x\rangle## The adjoint of position operator acts as ##\left\langle x\left|\hat{x}^{\dagger}=x<x\right|\right.## Then using above equation we've...

Q1a) - My current wrong answer is <-5.9e7, -3.3e8, -2.17e8> I used the Fnet = Gm1m2 / d^2 <unit vector> But i keep getting a dif answer each time Q2a) - I thought i could find net force and then divide it by the mass, and multiply it by the time interval. However I got the answer <-4.5, 4.5...

How much does a Cloud Computing position earn in Austria in general? I need this answer for an interview in order to negotiate with the interviewers. I hold a PhD degree in Physics but with no experience in the field.

I tried using the formula for the refraction of a spherical lens ##\frac{n_1}{p}+\frac{n_2}{q}=\frac{n_2-n_1}{R}## consider each slab as a spherical lens with curvature ##R=\infty## and by doing that I get ##\frac{1.33}{10}+\frac{1.5}{q}=0\Leftrightarrow q\approx -11.3 cm##. Since the piece of...

Hi all I am interested to know how Aircraft born 'On Top Position Indicator (OTPI)' works for RF emitter (e.g. Sonobuoy) localisation? As per my understanding, the Direction Finding systems used in OTPI gives only bearing of incoming RF signals (no range measurement), how the exact position of...

I am trying to follow the solution to the following problem, both linked in the attachment. When trying to find the acceleration, a, that should be taking the derivative of r, the position formula twice. When doing so I get v = -ksinθ and a = -kcosθ. The attached work shows v being -(ksinθ)θ'...

Lets take the original position of the man to be our origin The plank is uniform so we can assume its mass to be concentrated at its center i.e. 4m from the origin Xcom= m1x1+m2x2/m1+m2 =50(0) +150(4) /50+150 =3m There is no external force on the system so the centre of mass does not move...

I know that I have heard that GR proves that there is no absolute time, so does this go for location too? If so, could it be said that particles have a superposition in position/location the same way that particles do in QM?

Hi all In the Lagrangian, we have L = KE - PE In most cases, I have seen KE as a function of q and q-dot (using the generic symbols). However I first learned how KE = 0.5 m * v-squared. Later, I used generalized coordinates and THAT is when KE became a function of q. I get all that...

Summary:: Averaging (a power of) semimajor axis to position ratio wrt to time - celestial mechanics I evaluated it this far, but i don't know how to change the dt to d theta ... the final solution is supposedly (1-e^2)^-(3/2) . Any help will be appreciated. [Image re-inserted with correct...

Hi! Given three voltages as follows; Q1 = 1C,Q2 = 1C,Q3 = 2C The distance a is 1m and b = 2m a) Find the values of the forces that are acting on Q2 I did that like this; $$ F_{12} = \frac{Q1*Q2}{4\pi\epsilon r^2} $$ $$ F_{32} = \frac{Q1*Q3}{4\pi\epsilon r^2} $$ The results are ...

I started a project, and where I thought I has a potentiometer position feedback, best I can tell I have an eddy current position sensor, which I'm absolutely not familiar with The application is a diesel engine injector pump (retrofitting to a different engine, it was from a Komatsu V12, no, I...

So the acceleration of point A was given by a force F exerted on cylinder that's along the direction of the stick, decomposed into the horizontal direction. so aA = F cos Θ The same force along the opposite direction is exerted on stick, and if we decompose that in vertical and horizontal...

I had an equation. $$T=\frac{1}{2}m[\dot{x}^2+(r\dot{\theta})^2]$$ Then, they wrote that $$\mathrm dr=\hat r \mathrm dr + r \hat \theta \mathrm d \theta + \hat k \mathrm dz$$ I was thinking how they had derived it. The equation is looking like, they had differentiate "something". Is it just an...

a) ##T_A=\frac{p_AV_A}{nR}=300.7K, P_A V_A=kL^2=nRT_A##, ##P_B S=k\frac{L}{2}\Rightarrow P_B V_B=k(\frac{L}{2})^2 \Rightarrow P_B=\frac{kL^2}{2V_A}=\frac{P_AV_A}{2V_A}=\frac{P_A}{2}##, ##W_{spring\to gas}=\int_{L}^{L/2}kxdx=-\frac{3}{8}kL^2=-\frac{3}{8}nRT_A####\Rightarrow Q=L+\Delta...

$$\sum_i m_ir_i$$ Why the term always vanishes? There's some more equations where the mr was vanished. But, they didn't explain why it vanish. Why the term vanish? I think that's for position 0,isn't it?

Hi! I would like to know how I could define an equation for α with given the two lengths of the rods and angle theta (θ). I sketched the situation below, the problem arises when the rod Lab has pasts the 180 degrees. Like to hear.

Does the position of the origin for the body’s rotating coordinate frame 1) stay fixed to the moving body or 2) does it stay fixed to the inertial frame, yet still able to rotate as the body rotates with the only restriction that it cannot translate with the body i.e. only affixed at the...

It is said that: It is not possible to write a position vector in a curved space time. What is the reason? How can one describe a general vector in a curved space time? Can you please suggest a good textbook or an article which explains this aspect?

Let's same I have an observer A and B that initially occupy the same point at ##t=0## but they have a relative velocity to each other. Now let's assume there is an object C that moves in a circular motion around some point from A's frame. The initial condition/position is given (in A's frame)...

Hi everyone, for a lab I need to determine the position of the cardinal points of a telephoto lens. The focal points were determined experimentally, and the focal length given on the lens is 200mm. The principal points should be determined with f=PF. In all the textbooks, the principal points...

That is part of the article. I want to ask about step 4. I know the basic theory of how stationary wave is formed (superposition of incoming and reflected wave) and also basic concept about stationary wave in open and closed tube, something like this: But I don't know the reason why in step 4...

Hello, Apologies if this is in the wrong section, it's related to circles so I figured Geometry was the best place. I found a very good example online that explains how to determine a future position of an object undergoing uniform circular motion: (Note that they made a mistake by writing...

The graph: 1) $$v_1 = \frac{\Delta{x}}{t} = \frac{5 - 3}{3} = \frac{2}{3}$$ $$2 = \frac{\Delta{x}}{t} = \frac{4 - 0}{5 - 1} = 1$$ $$\frac{v_2}{v_1} = \frac{1}{2/3} = \frac{3}{2} = 1.5$$ 2)Points of intersection of the lines with the x-axis: ##I## (0; 3) and ##II## (0; -1), thus $$\frac{2}{3}t...

I have a construction made from 4040 aluminum extrusion. The top frame is opening at 90deg with external hinge. the weight of the top is 6Kg The dimensions are 50X75cm externally and 42X67 internally (as the frame width is 4cm) If pictures with dimensions would help please let me know.

So there's this idea in mountain biking that keeping your weight over the tire contact patch equates to more cornering traction. What I mean is instead of leaning with the bike, you lean the bike under you while staying mostly over the tires (see the right "Bike more than body" image below)...

Savings Analysis Please proceed with the following calculations, based on the data you can find in the attached Excel sheet: Forecast the ARPUs for voice services by country: Determine the ARPU discounts that are needed by country in order to deliver cumulative reduction of 27% by the end of...

For the sake of this question, I am primarily concerned with the position wave function. So, from my understanding, the wave function seems to 'collapse' to a few states apon measurement. We know this because, if the same particle is measured again shortly after this, it will generally remain in...

Attached is the problem and my work through the problem. I got the problem correct, but my teacher said this could be done quicker on a calculator. Any idea how it could be done quicker.

1.)##\dot{\vec{r}}=\dot{x}\hat{i}+\dot{y}\hat{j}+\dot{z}\hat{k}=\dot{r}\hat{r}## since the unit vector is constant 2.) ##\dot{r}\hat{r}=\frac{x\hat{i}+y\hat{j}+z\hat{k}}{\sqrt{x^2+y^2+z^2}}\frac{\dot{x}x+\dot{y}y+\dot{z}z}{\sqrt{x^2+y^2+z^2}}##...

a. The piston will be at rest when all its kinetic energy converted into work to push the gas, so: $$\frac{1}{2}m_0 c^2=P_0. \Delta V$$ $$\frac{1}{2}m_0 \frac{29}{4} \frac{P_0.V_0}{m_0}=P_0.\Delta V$$ $$\frac{29}{8} V_0=\Delta V$$ $$\frac{29}{8} L_0 = L_0 - L$$ $$L=-\frac{21}{8} L_0$$ My...

Say I have a rod with a notch at the very centre and another ro with a notch at the very end. Both rods are identical in length radius materials etc. Who would be impacted by the notch more? And if then both were to support a load at the end of the rod (both in tension), what effects would the...

In quantum mechanics there is no operator for time (problem with unbounded energy). position is no more an operator in field theory. was there still a problem in QM?