Momentum Definition and 1000 Threads

Homework Statement Homework EquationsThe Attempt at a Solution ## \frac { - d \phi }{dt} = V ## V denotes emf. The current is in ## \hat \phi ## direction. Magnetic force is along ## ~\hat s ## direction. Where ## ~\hat s ## is the radially outward direction in cylindrical...

In the original EPR paper momentum was giving as an example of entanglement, but I don't see that discussed by any thread or papers for that matter, why is that. What is the technicalities of this entanglement for two electrons for example, is it also instantaneous and why is it not used to...

Homework Statement Homework Equations E = γmc2 p = γmv K = E - mc2 E2 = c2p2 + m2c4 The Attempt at a Solution I have completed most of this question, but I am struggling to get the required result to the final part of the question.[/B]

Hi all, My question is in reference to the following paper: https://arxiv.org/pdf/1202.1783.pdf In equation 3.8, the author computes an order-of-magnitude approximation of probability of measuring negative momentum from the following wavefunction: $$ \Psi_k =\sum_{k=1,2}...

Homework Statement A particle in one dimension is in the ground state of the potential well given by V(x)= 0 for |x|<L/2 and infinite otherwise. Let P+ be the probability that the particle is found to move along the positive x direction and p be the magnitude of the momentum for that state of...

Homework Statement A hockey player hits a slap shot, exerting a constant force on a 3.06 kg puck for 0.06 seconds. What is the change in momentum of the puck? Homework Equations Impulse = Mass x (Change in velocity) = Force x time (I think that’s all needed? Most likely missing one.) The...

I have a question about momentum vs kinetic energy. For example, a block C with velocity Vc and mass=2m hit a block B with mass=m at stand still on a LEVELED frictionless track( no change of potential energy). The two block stick together and move at velocity Vcb. Find the relation of Vc vs...

Homework Statement Two blocks with masses 1 kg and 4 kg respectively are moving on a horizontal frictionless surface. The 1 kg block has a velocity of 12 m/s and the 4kg block is ahead of it, moving at 4 m/s. The 4 kg block has a massless spring attached to the end facing the 1 kg block. The...

Homework Statement this has been bugging me for a while now the angular momentum about any point p is given as ## \vec {L_p} = \vec {R_{cm,p}} \times \vec {P_{cm}} + L_{cm}\\ ## now if the body precessing around z axis and spinning about its own axis then angular velocity of body in lab...

1. Two particles P and Q are moving in opposite directions along the same horizontal straight ine. Particle P is moving due east and particle Q is moving due west. Particle P has mass 3m and particle Q has mass 2m. The particles collide directly. Immediately before the collision, the speed of P...

Homework Statement A system has total angular momentum L about an axis O. Show that the system's angular momentum about a parallel axis O' is given by L'=L-h×p, where p is the system's linear momentum and h is a vector from O to O'. Homework Equations L=r×p or considering a mass element...

Homework Statement Hello, Here is a multiple choice question I would like to be clarified. Suppose that the angular momentum of a system can take the values 0, 1, 2. One carries out a measurement of ##J_z##,the state of the system will: ##a##-Be perfectly known if the result is 0 ##b##-Be...

Homework Statement A uniform thin rod of Length L and mass M can freely rotate about a point 0 and is at rest in at the vertical. A ball of mass m on a light string of length R, which is also attached about the pivot is deflected by a small angle from the vertical and let go of. If the...

Hello, Suppose that the angular momentum of a system can take the values 0, 1, 2. One carries out a measurement of ##J_z## on this system. What can be said about the state of the system after the measurement? To what extent can it be perfectly certain if ##J_y## and ##J_x## do not commutate...

Hi all, I understand the mathematics behind special relativity pretty well, but I only have a bare conceptual understanding of general relativity. My understanding is that energy, momentum and stress (as described in the energy-stress tensor) are what contribute to space-time curvature and...

Hi everyone, hopefully someone will be able to point me in the right direction with this problem, I get as far as combining the two equations together and no matter how I rearrange them they don't seem to cancel nicely and leave me with an awful quadratic, I can find vx, but the question...

Homework Statement A car of mass 1500 kg is at rest on a platform of mass 3000 kg, which is also at rest. The platform has frictionless wheels attached to its bottom. The whole system is initially at rest. The car starts to move forward at a speed of 5.0 m/s with respect to the ground...

Can a reasonable observable operator be defined which measures a two-component observable, first component for the approximate coordinate and the second for the approximate momentum (so that the precision of each measurement do not contradict Heisenberg inequality)? I am actually thinking of...

Water is flowing inside a garden hose. The hose is bent at some point, i.e., it has the shape of L. What is the direction of the force applied by the water on the hose around the bend? (Let's say that one of the arms of the L goes along +x direction and the other arm goes along the +y direction...

One of the reasons I've been so stumped about learning about angular momentum in QM, is that in my classical physics class we only applied it to circular motions. Hence, while I am aware that angular momentum is connected to spherical harmonics, the orbital shapes (besides s) isn't really...

Hi, good afternoon the problem is this: This device was assembled with the purpose of calculating the torque of a small motor. It measures the force F through a charge cell. The calculations performed for the moment were made using the data provided by the load cell and distance "d". However...

Hi there, so I'm not sure if this is allowed or not, but usually before I submit my work I try to check it on the internet to get full marks. I do the work as best as I can to try and get the best understanding of the subject possible. I think a) is correct but I think I messed up somewhere in...

Homework Statement A single electron atom has the outer electron in a 4f1 excited state. Write down the orbital and spin angular momentum quantum numbers and the associated magnetic quantum numbers for this state. Homework Equations I don't think there is any relevant equations. I think it...

Homework Statement I have an issue with understanding the idea of generalised momentum for the Lagrangian. For a central force problem, the Lagrangian is given by, $$L = \frac{1}{2}m(\dot{r} ^2 + p^2 \dot{\phi ^2}) - U(r)$$ with ##r## being radial distance. The angular momentum is then...

I am trying to create a momentum trap to calculate the velocity of a projectile when it hits the trap. It essentially consists of a plate if known mass at the bottom of a pendulum of known radius. When the projectile hits the plate, the degrees that the pendulum rotates are recorded. I believe...

<Moderator's note: Moved from a technical forum and thus no template.> I am trying to design and perform a physics lab. It needs to show the relationship between torque and angular momentum. I have gotten as far designing a 4" PVC coupling and have it on a ramp. I am not sure where to go from here.

Homework Statement A school playground has a carousel, which is simply a circular platform that can rotate around its center axis with negligible friction. This carousel has radius r=1.6 m and rotational inertia I= 177m^2kg. Suppose you are standing beside the carousel which is already spinning...

Homework Statement A hydrogen atom is in the 7f state. What is the magnitude of its orbital angular momentum? Homework Equations L=sqrt(L(L+1)hbar The Attempt at a Solution L= Sqrt(3(3+1)Hbar) 1.41hbar (we want J*S) 1.41*1.054*10^-34 1.47*10^-34J*S

Given a wave function $$\Psi(r,\theta,\phi)=f(r)\sin^2(\theta)(2\cos^2(\phi)-1-2i*\sin(\phi)\cos(\phi))$$ we are trying to find what a measurement of angular momentum of a particle in such wave function would yield. Attempts were made using the integral formula for the Expectation Value over a...

Homework Statement Lee is riding on her 6 kg skateboard with a constant speed of 2 m/s. She jumps off of her skateboard and continues forward with a velocity of 4 m/s relative to the ground. This causes the skateboard to go flying forward with a speed of 18.5 m/s relative to the ground. What is...

Homework Statement I need to find the intial velocity of a ball, given the angle the pendulum bob swings through. I need to derive this equation. [/B] V0=4.43mtotalL1/2{1-cosΔθ}1/2/mball Homework EquationsThe Attempt at a Solution I have barely any attempts since I can't even think where to...

Homework Statement Why is the magnitude of Angular Momentum for an elliptical orbit as such? $$l = mr^2\dot{\phi}$$ where ##\dot{\phi}## represents angular momentum. I have always assumed that angular momentum was $$l = r \times P = mr \times V = mrVsin(\theta) = mr^2\dot{\phi} sin(\theta)$$...

Homework Statement You decide to design a bicycle that will have only 3/4 of the angular momentum of the original wheel when both wheels are traveling along a road at the same velocity. The original wheel had a diameter of d1=37cm and rotational inertia of I1=0.32 m2kg. If your new wheel has a...

1. The problem statement Consider a particle of mass m under the action of the one-dimensional harmonic oscillator potential. The Hamiltonian is given by H = \frac{p^2}{2m} + \frac{m \omega ^2 x^2}{2} Knowing that the ground state of the particle at a certain instant is described by the wave...

https://drive.google.com/file/d/1Z-avhDqYbxDtMzk6Rv_NES7rIvDmzMPz/view?usp=drivesdk 2.conservation of angular momentum 3.for the above question I tried applying conservation of angular momentum about the point of contact where the cyclinders touch each other but my answer does not match with...

Homework Statement Derive the differential momentum equation: dp=-\rho udu. Homework Equations \oint_{ CS}^{ } \rho \vec{U}(\vec{U}\cdot \vec{n})dA=-\oint_{ CS}^{ } p\vec{n}dA for steady state flow... The Attempt at a Solution I tried to solve it like in the attached picture, but can someone...

A person standing on a stationary friction-less turntable spins a bicycle wheel with the rotation axis of the wheel in the horizontal direction, thus the initial angular momentum is in the horizontal direction (x - axis), say to the right. Now suddenly the person turns the axis of rotation of...

Homework Statement In my reference frame, I see two carts collide. Both cart A and Cart B have a mass of 2 kg. Cart A has initial velocity v= 3 m/s i-hat + 2 m/s j-hat, cart B has initial velocity v= 3 m/s I-hat + 4 m/s j-hat. 12 J are released in the collision. In previous parts of this...

Homework Statement A uniform thin rod of length ##2l## and mass ##m## lies on a horizontal table. A horizontal impulse ##J## is given to the rod at one end. There is no friction. The total kinetic energy of the rod after impulse will be ? Homework Equations ##Jl=I\omega## ##J=mv_{cm}##...

I understand for linear momentum the measure of the dificulty to take a body to the rest. But when I do the next exercises, I find that it requires less force for one body compared to the other with same linear momentum. Can someone explain me what to understand in an intuitive way what to...

Homework Statement According to the Big Bang model of cosmology, the universe has been expanding since some initial time (call it t = 0) when the temperature was infinite. At early times, the temperature T scales as t^1/2 . The current temperature is about 3K. Consider the part of space which...

Homework Statement Three small, identical 0.70-kg pucks are attached to identical 0.50-m strings, tied together at a common center as shown in (Figure 1) . Pucks are whirled in circular motion at angular speed 3.0 s-1 What is the magnitude of the angular momentum of the system about the...

Hi, Apologies if this questions is really easy but it is something quite subtle which is annoying me. In my book of quantum physics it gives a wave function of definite momentum: ψ = Aeipx/ħ It goes on to say that since there is a momentum 'p' in the exponential then the momentum is known...

Homework Statement In the figure, a 0.400 kg ball is shot directly upward at initial speed 58.3 m/s. What is its angular momentum about P, 1.42 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 A disk with a rotational inertia of 8.38 kg·m2 rotates like a merry-go-round while undergoing a torque given by τ = (5.03 + 1.01t) N · m. At time t = 1.00 s, its angular momentum is 6.57 kg·m2/s. What is its angular momentum at t = 3.00 s? Homework Equations dL/dt= T...

Hello guys. So this is less about about the physics problem and more about the concepts behind it. I don't need help with any solution but I am framing my questions around the example given. So there are two steel balls with equal mass that are hanging from a point by a string. Both strings are...

It explains very well many aspects of the Universe. Why should there be any angular momentum though? The idea that the Universe is itself intrisically rotating doesn't make sense.

Good evening, Does anybody know how to get the units of momentum flux? Momentum = kg m s−1 Flux = m−2 s−1 Somehow, I should end up with kg m-1 s-1 (kg m s−1) m−2 s−1 = kg m−1 s−1 However I end up with kg m-2 s-2 Is there anybody that knows what I'm doing wrong? :)

Homework Statement A rocket, weighing 43,600N, has an engine that provides an upward force of 120,000N. It reaches a maximum speed of 860 m/s. For how much time must the engine burn during launch in order to reach this speed? Homework Equations p=m*Δv i=F*t The Attempt at a Solution I started...

Homework Statement Three freight cars of equal mass are coupled together. The freight cars are traveling at 6.7m/s down a straight track when they collide with two more stationary identical cars. If all five cars are coupled together after the collision, then what is their speed if they are on...