Angular momentum Definition and 1000 Threads

I know that the angular momentum of the moon with respect to the Earth can be calculated by L = Iw but if the L of the moon is k * Learth-sun the there will be way more eclipses, one of each every 28 days. So the momentum of the moon must change over time, how does it work?

Hi, I need any good books or articles about the mathematical analysis and modelling of orbital angular momentum Regards

Homework Statement Show that the quantization of angular momentum implies that the kinetic energy of the electron is quantized as K=nhforb/2, where forb is the frequency of rotation. Assume circular orbit. Homework Equations Radial acceleration: arad = v2/r = (4π2r/T = 2*π*v/Tr = nħ KE =...

Homework Statement A girl places a rock in a sling and begins spinning it in a circular path above her head. By exerting a force on the sling, she increases the rock's speed while it goes around her head a few times, before releasing the rock. Options: 1. She exerts a force on the rock that is...

Hi everyone, I tried to find the Eigenstate of the angular momentum operator myself, more specifically I tried to find a Function Y_{lm}(\theta,\phi) with L_zY_{lm}=mħY_{lm} and L^2Y_{lm}=l(l+1)ħ^2Y_{lm} where L_z=-iħ\frac{\partial}{\partial \phi} and...

So is a Bike driver stable when the bike is running because the bike wheels has a certain moment of inertia about the horizontal axis ,which might alter(mi gets lesser) if the direction of the axis changes ? Thanks in advance

As another of my personal music projects, I have wondered if it would not be possible to calculate the 'feel' of a drumhead (i.e. the amount of 'give' expressed as transverse displacement 'z' that an equally pre-tensioned circular membrane of radius 'r' experiences when struck on its plane at a...

A rod of length L and mass M is rotating with angular velocity w about its center of mass. What is its angular momentum with respect to a rotating point 1/4L from the rod's end? What about a stationary point? Homework Equations With the respect to the center of mass, angular momentum L = Iw =...

Hi, not a homework problem as such, but I am studying introductory quantum physics and having some trouble understanding how applying the rising or lowering operator for angular momentum implies: L+/-|l,m> ∝ |l, m+/-1> Basically, my question is the same as the first part (Q1) as described in...

Homework Statement Two discs of different radii and masses are kept on a smooth horizontal table and both are free to rotate about their fixed central vertical axis. One of them is given some angular velocity while other is stationary. The rims are brought in contact. There is friction between...

I'm trying to find out if this is angular momentum or something else. It says this, "If an object spins in a certain direction any pieces that break off that object must also spin in the same direction." Is that angular momentum or something else?

Hi, Some "derivations" of the law of the lever argue with conservation of energy: If one arm of the lever of length ##r_1## is pulled by a distance ##s_1## with force ##F_1##, the other arm moves by a distance ##s_2=s_1 \frac{r_2}{r_1}##. From conservation of energy ##E=F_1 s_1=F_2 s_2## it...

Homework Statement Given a reference frame O' moving at a constant speed $\vec{V}$ in relation to another reference frame O, I want to prove that ##\vec{r_{1B}} \times m_1\vec{v_{1B}} + \vec{r_{2B}} \times m_2\vec{v_{2B}} = \vec{r_{1F}} \times m_1\vec{v_{1F}} + \vec{r_{2F}} \times...

Homework Statement The problem deals with a charged (Q) rotating sphere around its axis (Ω_0) z^^ (z hat) of radius a. I'm asked to find the total angular momentum of the EM fields. 2. The attempt at a solution There is a solution posted to this question and I was just wondering why my...

Will the angular momentum of a half filled waterbottle increase? or decrease? or remain the same?

Say, I have two spin-1/2 particles in the states characterized by ##(n=2, l=1, m_l=1, m_s=1/2)##and##(n=2, l=1, m_l=1, m_s=-1/2)##. Now, using something like the jj coupling scheme, I first find out the (orbital+spin)angular momentum for the individual particles:(i) ##| 11\rangle...

Homework Statement The momentum carried by an electromagnetic field is [;\vec{P}(\vec{x}, t) = \frac{1}{4\pi c} \int d\vec{x}\vec{E}(\vec{x},t) \times \vec{B}(\vec{x},t);] show that for a finite field extension [;\vec{J}(\vec{x}, t) = \frac{1}{4\pi c}\int -i...

Two hollow spheres, both the mass and radius R M , which are rotating around a center of mass ( CM ) , with an initial period To, are kept distant from each other by an ideal wire with a distance of 8R. At a given instant a motor is driven by wrapping the wire and making the two spheres meet...

Homework Statement I've a physical system with ##l=1## and I have to calculate the values I can obtain if I measure ##L_x## and their probability.Homework Equations I know that: - the values I can obtain are ##\ m=0, \pm 1## - ##\displaystyle L_x=\frac{L_+ + L_-}{2}## - ##L_x|1, m>_x=\hbar m...

Hello, I've recently came across this video (), where the authors use a motor to compress springs and therefore achieve locomotion. I've been thinking why is there a resulting downward net force. But i can't really figure it out. Thank you for time :) See the video from 1.16 minutes and...

Homework Statement A counterweight of mass m 5 4.00 kg is attached to a light cord that is wound around a pulley. The pulley is a thin hoop of radius R = 8.00 cm and mass M = 2.00 kg. The spokes have negligible mass. When the counterweight has a speed v, the pulley has an angular speed v = v/R...

Homework Statement A uniform cylinder of mass M and radius R can be rotated about a perpendicular axle through its centre. A particle of mass m is attached to the cylinder's rim. The system is rotated with angular velocity w about the axle, which is held in a fixed direction during the motion...

I've searched a little bit and found that I can derive kepler's third law from Newton's law of gravitation. That's okay. But I want to deduce kepler's second law too: "An imaginary line joining a planet and the sun sweeps out an equal area of space in equal amounts of time". I know it's possible...

Assuming R-pairity and thus the creation/destruction of supersymmetric particles happens in pairs, how is angular momentum conserved when a particle and its supersymmetric partner have different spin by 1/2?

Suppose a mass ##m## is attached to the end of a string whose other end is attached to a cylindrical pencil. The mass is then spun around the pencil in a circle (whose centre coincides with the centre of the pencil) such that the string wraps around the outer surface of the pencil, thereby...

Hopefully the image is self-explanatory, if not: A cylinder is rotating around its central axis with angular momentum L1; an angular impulse, ΔL is then added to the cylinder, perpendicularly with respect to L1. The hypothetical result is: the cylinder has one angular mometum at the end...

Let's start with an arbitrary solid body rotating around a fixed axis of rotation with angular velocity ##\vec \omega## in the ## \hat z## direction. For simplicity, let's say the origin O is on the axis of rotation. Take a look at the picture I sketched in the next post. Tried my best to be...

< Mentor Note -- thread moved to HH from the technical physics forums, so no HH Template is shown >[/color] Hey, So I am not sure if this is in the right section but feel free to move it. We are conducting an experiment at school at the moment and are having difficulty understanding all the...

Hello people, I have a question regarding black holes. The way i understand it, black holes form in supernovas, and they occur because the gravitational pull of the stellar remnant is so great that nothing can stop it, and it basically collapses down to a singe point, virtually nothing... Now...

Say a ring is spining around the z-axis, an angular impulse is then applied to it in the x-axis, what is the resultant motion qualitatively and quantitatively? How can it be calculated? (You can make up the quantity of z-angular momentum and x-angular impulse)

I am modelling the attitude dynamics of a satellite. The satellite has a reaction wheel in 1 plane to help control the attitude. There is significant debate about the equation for the net angular momentum of the satellite and what inertia tensors should be used regarding parallel axis theorems...

Lets say one gear is rotating with some angular velocity and its angular momentum vector is pointing up. A second gear (not rotating) is then allowed to mesh with the first. The second gear has the same radius and moment of inertia as the first. Is not the angular momentum vector of the second...

I've been tutoring for chemistry and someone asked me to clarify the difference of spin angular momentum and orbital angular momentum without math. I was trying to think of a metaphor, but I wanted to make sure it's a fair one--the spin angular momentum is like Earth rotating on its own axis...

Hi all, Quick quantum question. I understand the total angular momentum operation \hat{L}^2 \psi _{nlm} = \hbar\ell(\ell + 1) \psi _{nlm} which means the total angular momentum is L = \sqrt{\hbar\ell(\ell + 1)} But how about applying this to an arbitrary superposition of eigenstates such as...

Hoping this is in the right section! The module is nuclear and atomic physics but it crosses over into quantum occasionally. I've attached an image of the bit I'm trying to work out. I've got an exam on this topic in just over a week, so sorry if these posts get annoying, I have a feeling I'm...

Homework Statement A 1.0 kg particle is moving at a constant 3.5 m/s along the line y=0.62x +1.4, where x and y are in meters and where the motion is toward the positive x and y directions. Find its angular momentum about the origin2. Attempt at a...

Homework Statement A rod of length l and mass M is suspended from a pivot, as shown The rod is struck midway alongs its length by a wad of putty of mass m moving horizontally at speed v. The putty sticks to the rod. Find an expression for the minimum speed v, that will result in the rod’s...

Homework Statement In the figure, a 0.400 kg ball is shot directly upward at initial speed 40.4 m/s. What is its angular momentum about P, 6.65 m horizontally from the launch point, when the ball is (a) at maximum height and (b) halfway back to the ground? What is the torque on the ball about P...

Homework Statement Homework Equations L = mvr L = Iw The Attempt at a Solution I did not attend this lesson due to some reasons. I read it from the book but I could not understand it well. I know the linear momentum well. However, in angular momentum, we have two equations I don't know...

<< Mentors have notified the OP to show their Attempt at a Solution >>[/color] 1. Homework Statement A uniform rod of length L1 = 1.5 m and mass M = 2.8 kg is supported by a hinge at one end and is free to rotate in the vertical plane. The rod is released from rest in the position shown. A...

So my question is when to apply conservation of angular momentum?When there is no external force ,right?But in the case below A mass m moves in a circle on a smooth horizontal plane with velocity v0 at a radius R0. The mass is attached to a string which passes through a smooth hole in the plane...

I am hesitant to write this post. I am a bit overwhelmed that many members have questions of a higher level. They may be reading scientific journals. My question is very basic. I might be called stupid. Coming to the question. Is angular momentum same as spin of an electron?. But I read that...

OK, so I'm right in the middle of watching Interstellar and I've just seen the part where they have docked with the 'mothership' and they fire up their engines to get it to rotate. This is so they can generate a centrifugal force to simulate gravity. My question is - first the ship was not...

Hi, I've been wondering is there anyway of calculating the angular speed of a ball after there is a collision of it and another mass. For example a baseball bat hitting the ball. I have not looked up on angular momentum, but is angular momentum involved in this? Based on common sense, I think...

The definition of orbital angular momentum, whether for classical mechanics or for quantum mechanical operators, is rxp. Technically, according to this definition, one particle can possesses orbital angular momentum - in this case about the origin. But I cannot think of any examples, in...

Homework Statement A uniform rod of mass 3.15×10−2kg and length 0.380m rotates in a horizontal plane about a fixed axis through its center and perpendicular to the rod. Two small rings, each with mass 0.250kg , are mounted so that they can slide along the rod. They are initially held by catches...

Hi All, Is the Angular momentum conserved at the singularity ? Thanks in advance

Hi, I'd like to know how to calculate parity and total angular momentum of nuclei which have even Z and even N and also Z and N are magic numbers, such as 8O8 or 20Ca20 (the number before the element is Z and the after one is N). I don't know how to insert LaTeX formulas. Thank you in andvance

Hi. For the angular momentum l=2 case are the L2 and Lz matrices both 5 x 5 matrices with the following eigenvectors ? ## \begin{pmatrix} 1\\0\\0\\0\\0 \end{pmatrix} ## , ## \begin{pmatrix} 0\\1\\0\\0\\0 \end{pmatrix} ## , ## \begin{pmatrix} 0\\0\\1\\0\\0 \end{pmatrix}##,## \begin{pmatrix}...

A vector operator ##\mathbf{V}## is defined as one satisfying the following property: ## [V_i,J_j] = i\hbar \epsilon_{ijk}V_k## where ##\mathbf{J}## is an angular momentum operator. My question is what is the role of ##\mathbf{J}##, does it have to be the total angular momentum from all...