Position Definition and 1000 Threads

I got this question in an exam. Why do silent mutations always affect the third position of a codon? I have no clue about it.

Homework Statement 1m diameter solid disc spinning at 10 rpms with a subsequent .5m diameter solid disc being driven by the 1m sokid disc. Homework Equations Not sure there is one for my particular situation. The Attempt at a Solution Just using the torque is equal to force times distance...

Homework Statement Consider a particle which is confined in a one-dimensional box of size L, so that the position space wave function ψ(x) has to vanish at x = 0 and x = L. The energy operator is H = p2/2m + V (x), where the potential is V (x) = 0 for 0 < x < L, and V (x) = ∞ otherwise. Find...

Homework Statement The position of a participle in a fixed inertial frame of reference is given by the vector r = i(x0 + Rcos(Ωt)) +j(Rsin(Ωt))where x0, R and Ω are constants. a) Show that the particle moves in a circle with constant speed Homework Equations F = mv2/r The Attempt at a...

Homework Statement There is a particle that moves in 1-dimension. mass is m, force on the object is given as a function of position(x), Fx= -mω2x.(ω is constant) when t=0 particle has x0>0, and velocity is zero. find the particle's position as a function of time. Homework Equations There is a...

Hi all! I'm an undergrad in physics in the USA, and a research professor I've been working with for the past ~2 years is applying for an open faculty position at an Australian university. She hasn't asked me to recommend her in any way, and I know that in all likelihood the word of some...

Homework Statement Use the graph (attached below) to determine the time intervals when the velocity is positive, negative, or zero. Homework EquationsThe Attempt at a Solution The graph is of a position function. Velocity is the derivative of position. Velocity will be zero when the derivative...

Hello, I am trying to find a function x(t) that describes a particle falling into a gravitational well from a certain distance. So, for example, I am trying to figure out the differential equation: F = m*(dx^2/dt^2) = -GMm/x^2. Or simply, dx^2/dt^2=-GM/x^2 or even more simply, x''(t)=-k/x^2...

Homework Statement For my question, I am following a previous method I used in my HNC where I had to determine the position and magnitude of the maximum bending moment. I am now working on my project and I have revisited this question but I am having some issues in my method. The above diagram...

Homework Statement I want to prove that ##\frac{\partial \langle x \rangle}{\partial t} = \frac{\langle p_x \rangle}{m}##. Homework Equations $$i\hbar \frac{\partial \Psi}{\partial t} = -\frac{\hbar^2}{2m} \frac{\partial^2 \Psi}{\partial x^2} + V \Psi$$ The Attempt at a Solution [/B] So...

Homework Statement By relative velocity, we mean velocity with respect to a specified coordinate system. (The term velocity, alone, is understood to be relative to the observer’s coordinate system.) (a) A point is observed to have velocity Va relative to coordinate system A.What is its...

Homework Statement The position of a particle as a function of time is given by x=Acosbt, where A and b are constants. The first question asks to roughly plot the position of the particle over the time interval (0,7) seconds. The second asks what time the particle passes the origin, and what...

Homework Statement A particle starts from x_0 = 14m at t_0 = 0 and moves with the velocity graph shown What is the object's position at t = 2 s? Homework Equations Area under velocity time graph is the displacement of the particle. The Attempt at a Solution The part that confuses me is where...

Hello! (Wave) At a clock (on which we have the positions $1,2, \dots, 12$) we place at position $1$ a blue ball and at position $2$ a red ball. At discrete times ($1,2,3, \dots$) we shift the two balls. Each time we shift the blue ball by three positions and the red ball by one position. Will...

I read that a force between two bodies can only depend on their relative position and relative velocity. But I can't understand in what is this statement leaning on and what it means.

In the first volume of his lectures (cap. 6-5) Feynman asserts that these 2 can be the PDF of velocity and position of a particle. Under which conditions it's possible to model velocity and position of a particle using these particular PDFs ? ps: Is the "Heisenberg uncertainty principle"...

According to the vector definition, the vectors have both the direction and magnitude such as displacement vectors which should possesses arrows on the top of them because they have displacement so they express a direction. On the other hand, position vectors are stationary, they do not have any...

[Mentors' note: This thread's prefix has been set to 'B'] We all know that the quote in the title is an imprecise convenience when talking about the Heisenberg uncertainty principle in a context where we would not want to enter into conceptual or fundamental issues to make a more correct...

Homework Statement A hypertriton (a bound system with a L hyperon together with a deuteron core (proton and neutron) is produced at the origin of the coordinate, (x,y)=(0,0) with a velocity of 0.94c (beta=0.94), flying along the x-axis. The mass of the hypertriton is 2.991 GeV/c2 . It decays...

I am confused about the difference between the two In Griffith's 2.3 The Harmonic Oscillator, he superimposes the quantum distribution and classical distribution and says What I understand for quantum case is that ##|\Psi_{100} (x)|^2## gives the probability we will measure the particle...

I was solving an exercise from Cohen's textbook, but then I got stuck in this question. "Let ψ(x,y,z) = ψ(r) the normalized wave function of a particle. Express in terms of ψ(r) the probability for: b) a measurement of the component Px of the momentum, to yield a result included between p1...

Homework Statement Homework Equations V = I R Q= CV The Attempt at a Solution When the switch is connected to position a : 20-106 * I = 0 ( KVL) Vc = 0 , because the switch is connected for a long time. I = 2*10-5 A When the switch is connected to position b : Q/(4*10-6) - 106 *2*10-5 = 0...

As I understand it, |Ψ|2 gives us the probability density of the wavefunction, Ψ. And when we integrate it, we get the probability of finding the particle at whichever location we desire, as set by the limits of the integration. But when we use the position operator, we have integrand Ψ*xΨ dx...

Hi, So there are very little Information Technology jobs around in my area according to indeed.com. I'm currently contributing to open source on GitHub (which is legally a job, but it's not a paid job). I'm really trying to get back into my field of computer science/information technology, but...

I have noticed a number of Skywatcher mounts in pictures posted on this thread so I guess there must be quite a few 'EQ' owners with loads of experience in these mounts. I know how to polar align and how to input location and time details. Also I often successfully do 3 star alignment and...

Hello PF, So in my country (Lebanon), we have this French system of education where masters come after Bsc. and then you can consider the Ph.D. position. Apparently, this is not the case in the US and one can get into a graduate program with just the Bsc. I know they are equivalent but if...

Homework Statement In an ac generator Voltage is maximum when the coil is parallel to the direction of magnetic field (B) Voltage is minimum (0) when the coil is perpendicular to the direction of magnetic field (B) I'm trying to understand why. Homework EquationsThe Attempt at a Solution A...

Hi, I've got this problem I'm trying to work out. The problem seems simple, but I don't think I have a good way to construct a way to solve it. This is the problem. Let P and Q be two points with position vectors p and q and let R be a point midway between these two. Find an expression for the...

Homework Statement Show that, for a general one-dimensional free-particle wave packet $$\psi (x,t) = (2 \pi h)^{-1/2} \int_{-\infty}^{\infty} exp [i (p_x x - p_x^2 t / 2 m)/h] \phi (p_x) dp_x$$ the expectation value <x> of the position coordinate satisfies the equation $$<x> = <x>_{t=t_0}...

Homework Statement I'm stuck on part (d) but I've included the previous subquestions in case they're useful. The length of an asteroid is exactly 300 m = 1 µls (micro light-second) when at rest. Draw a carefully labelled space-time diagram to illustrate the following: (a) Depict the rest...

I've been trying to understand why we see different milky way arms depending on where we are on Earth and what time of year it is. I've been googling and I can't find an answer. Can anyone explain this to me? If you have a picture handy that would really help. Thanks.

In Lagrangian mechanics, both q(t) and dq/dt are treated as independent parameters. Similarly, in Hamiltonian mechanics q and p are treated as independent. How is this justified, considering you can derive the generalized velocity from the q(t) by just taking a time derivative. Does it have...

Homework Statement Given ##\hat{x} =i \hbar \partial_p##, find the position operator in the position space. Calculate ##\int_{-\infty}^{\infty} \phi^*(p) \hat{x} \phi(p) dp ## by expanding the momentum wave functions through Fourier transforms. Use ##\delta(z) = \int_{\infty}^{\infty}\exp(izy)...

Homework Statement Consider the Wheatstone bridge as shown in the following figure, where ##e_0## is the Galvanometer reading. The condition for ##e_0 = 0 ## is called the null condition of the bridge. Using the Kirchhoff's rules, we can show that the condition is ## R_1R_4 = R_2 R_3##. Now I...

Homework Statement A particle is moving in a 1-dimensional harmonic osciallator with the hamiltion: ## H = \hbar \omega (a_+ a_- + \frac{1}{2})## at time ## t=0## the normalized wave function is given by ## \Psi(x,0) = \frac{1}{\sqrt{2}}(\psi_0(x) + i\psi_1(x)) ## Task: Calculate for ## t \geq...

I recently found this article about the dynamics of the wave function. It has some good simple illustrations and I found it valuable. But the author has a question himself, about understanding the Schrodinger equation. I wonder if anybody here could fill in the missing piece. The relevant part...

Homework Statement [/B] The position of a particle as a function of time is given by r(t) = i(1 - e^-kt ) + je^kt where k is a positive constant. Find the velocity and acceleration of the particle. Sketch its trajectory. Homework Equations v (t) = dr/dt a(t) = dv/dt The Attempt at a Solution...

Homework Statement Homework EquationsThe Attempt at a Solution I think none of the options are correct . It is a uniform motion between t=0 and t=2 sec. Velocity is constant . Impulse is given by m∆v .Since ∆v = 0 , impulse is zero at t= 2 sec . Is that correct ?

Hello, I'm a beginner on SGR and I'm struggeling with this, probably, simple problem. I'm interested on exploring Field Theory ( relativistic) so I started reading http://www.elegio.it/mc2/LandauLifshitz_TheClassicalTheoryOfFields_text.pdf which was suggested and reccomended by a PF's member...

What is the covariant derivative of the position vector $\vec R$ in a general coordinate system? In which cases it is the same as the partial derivative ?

<< Mentor Note -- poster has been reminded to do some reading on their own before asking simple questions at the PF >> Are clouds mostly in a specific height range from sea level? If yes, what is that height?

Homework Statement Homework EquationsThe Attempt at a Solution what's the Fa and Fb? my logic is Fa = Wa - N = mg - ##\frac{N}{\cos \theta}## so is Fb... so the ratio is 1. But I know it's wrong. What will make the difference between Fa and Fb? can anyone give a clue please?

Homework Statement "Can you arrange the two point charges q1 =−2.0×10−6 C and q2 =4.0×10−6 C along the x-axis so that E =0 at the origin?"Homework Equations E = K (|q|/r2) K = Coloumb Constant The Attempt at a Solution Since one particle is negatively charged and the other is positively...

Homework Statement The diagram is attached. What is the strength of the electric field at the position indicated by the dot in Figure 1? What is the direction of the electric field at the position? Specify the direction as an angle measured clockwise from the positive x axis. Homework...

In non-relativistic QM, when one speaks of a "wave function" it is understood that one is referring to the position-space version of the wave function. Even if the observable being measured is other than position, like momentum or energy, the associated eigenfunctions are always from the...

Homework Statement A spring has a relaxed length of 35 cm (0.35 m) and its spring stiffness is 10 N/m. You glue a 70 gram block (0.070 kg) to the top of the spring, and push the block down, compressing the spring so its total length is 12 cm. You make sure the block is at rest, then at time t =...

I forgot where I came across this and why I got so determined to figure it out but I wanted to ask about this d/dx(v^2) business. My question is to solidify my understanding of the chain rule with physics equations (sorry for crap terminology). Therefore, I know I use it and do the math as...

Homework Statement Homework EquationsThe Attempt at a Solution I took ## \frac { d\vec r}{dt} = 0 ## . This gives ##t_m = \frac { 1} {\sqrt{ 2}} ## ...(1) To calculate ## \alpha ## , ## \cos{ \alpha } = \frac { \vec v \cdot \vec r}{|\vec v||\vec r|} ## ...(2) Then, magnitude of...

Hello, some operators seem to "add up" and give real eigenvalues only if they are applied on the imaginary position, ix, rather than the normal position operator, x, in the integral : \begin{equation} \langle Bx, x\rangle \end{equation} when replaced by:\begin{equation} \langle Bix...

In the momentum representation, the position operator acts on the wavefunction as 1) ##X_i = i\frac{\partial}{\partial p_i}## Now we want under rotations $U(R)$ the position operator to transform as ##U(R)^{-1}\mathbf{X}U(R) = R\mathbf{X}## How does one show that the position operator as...