Momentum Definition and 1000 Threads

Homework Statement Homework Equations Li = Lf L = I*omega K = (1/2)*(I)*(omega)^2 The Attempt at a Solution [/B] Given that there are no non-conservative forces in action, I am assuming that the two kinetic energies should be equal. However, as shown by my work above, the two values...

Homework Statement If I want to find the difference in velocities of 2 objects A and B We know the sum of their velocities is A + B But but is the difference B - A Why not A - B? Homework Equations This is from the equation of calculating restitution where (greek letter) = (The difference in...

Homework Statement A cylinder with radius ##R## and height ##h## which has a distributed charge on its surface with density ##\sigma## spins over its axis with angular velocity ##\omega##. If the cylinder has a mass density ##\rho##, find the relationship between magnetic momentum and angular...

Homework Statement Find magnitude of momentum of both blocks Homework Equations p=mv The Attempt at a Solution I am doing my homework right now and just need help understanding finding the total momentum given a before collision/ after collision situation. So i am unsure if i should take the...

Homework Statement I've spent at least 1.5 hours on this problem trying to figure out what i did wrong and I can't find anything. With an exam in two days plus another chapter to go through. Regardless, here are the problem(6) and answer, as well as my work. Hope you can read it, and the...

1. Homework Statement in picture Homework Equations momentuma+momentumb=momentum of system The Attempt at a Solution So i just spent 1 hour trying to solve this problem and got completely stuck when trying to solve for the angle of ball 2 in the final position i ended up with an equation...

1. Homework Statement In picture above Homework Equations impulse = Δp[/B]The Attempt at a Solution 4.28NS = Δp 4.28NS = pfinal - pinitial 4.28NS + 0.18kg*0.16m/s = pfinal (4.28NS + 0.18kg*0.16m/s)/.18kg = vfinal vfinal = 39.77777778m/s Now i got the direction incorrect but the magnitude...

Homework Statement m = 50kg Distance covered = 100m T = 3.22 Solve for average momentum. Homework Equations X = 1/2 at^2 p = mass*acc*change time The Attempt at a Solution 100 = 1/2 a (3.22)^2 a = 200/10.3684 = 19.28937m/s^2 f = 50 * 19.28937 = 964.4689 change momentum = 964.4689 * 3.22 =...

I've learned that in a crystal, the crystal momentum is conserved. When one considers the electrons as Bloch waves, they have a momentum that doesn't commute with the Hamiltonian and they have well definite energies, hence they cannot have a well definite momentum, because there is no basis in...

In the derivation of F=ma, when we reach the point F=kma, we take k=1. Why can't we take 'k' as some other value? I will be thankful for help!

Homework Statement I have been asked to calculate the momentum of a photon in that has been ejected as a gamma ray after a nucleus was excited in terms of the Energy. I am confused as to whether or not I can use two different equations Homework Equations E=mc^2 or E=hf λ=h/p The Attempt at a...

Homework Statement There's a car, there's a cannon strapped on top of a car, the car travels with a velocity of 20 m/s and the cannon fires. The cannon fires a ball at 200 m/s. What is the velocity of the car? Velocities are with respect to the ground. mass car = 1000 mass cannon = 100...

Homework Statement Consider a rocket subject to a linear resistive force, $$f = -bv$$, but no other external forces. Use Equation (3.29) in Problem 3.11 to show that if the rocket starts from rest and ejects mass at a constant rate $$k = -\dot{m}$$, then its speed is given by: $$v =...

Homework Statement Homework EquationsThe Attempt at a Solution Hi All, My problem is that when I calculate this integral or use software to do it for me I get (3*i*pi)/16, when I've been told that the answer is 1/2i giving a probability of 1/4. Would someone be able to point out where my...

I explained this thinking to a meteorologist once and she couldn't give me an answer. Any physicists want to give it a shot? I find the typical explanation of tornadoes perplexing (that's a polite way of saying I don't believe it). The explanations I've seen claim that tornadoes start out...

Homework Statement Homework EquationsThe Attempt at a Solution How do I calculate part d? I know that (m2-m1)v0 = m2v2+m1v1 where v0 = root (2gh), v1 and v2 are the new velocity of the masses (m2+m1)v02 = m2v22 + m1v12 I also know that v2-v1=2v0 but how do I separate the KE of mass 2?

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)...

Hello all, I have a question regarding the precise definition of angular momentum in orbital motion. I see one definition says angular momentum h, position, r, and radial velocity, r_dot, are related as follows: h = r x r_dot. However, I also see one definition that says h is related to r and...

Homework Statement A 25kg child is spinning on a merry-go-round of mass 150kg and radius 2m at a constant angular velocity of 1rev/s. The child slowly walks to the center of the merry-go-round. Treat the child as a point mass and the merry-go-round as a uniform solid disk, and neglect friction...

I learned that the Poynting vector was the electromagnetic density of momentum but recently, while reading the Electromagnetic_stress–energy_tensor article at Wikipedia, I thought about the implications of the momentum conservation equation and arrived to an inconsistency, this equation is...

Homework Statement Hi I'm having trouble with a question that's asking me to calculate the precession rate for a spinning top. The trouble that I'm having is that I don't understand how the angular momentum points along the axis of the spinning top (picture attached). When I use the formula...

In QM, the inverse distance operator ##\hat{r}^{-1}## appears often because of the association to Coulomb potential. The operator of inverse momentum, ##\frac{1}{\hat{p}}## is a lot more rare. In the book "Exploring Quantum Mechanics: A Collection of 700+ Solved Problems for Students, Lecturers...

Homework Statement Homework Equations T = 2pi * sqrt(m/k) mv =m2v2 (LM)[/B]The Attempt at a Solution [/B] So T2 depends on the mass and not velocity. So i can find T2 = 2pi * sqrt([m/2]/k) For A2 , i know that the amplitude before any collision is 1/2m1v1^2 = 1/2kA1^2 so solving that, i...

Homework Statement 1. Two skateboarders start from rest on opposite sides of a ramp like the one in the image, roll down and collide elastically on the level part of the ramp. The masses of the skateboarders are m1 = 48 kg and m2 = 55 kg and they both start from the height h = 4.70m. Ignoring...

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 Homework Equations because their is steady flow we only care about mass flow flux meaning m1vout - m2vout m = ##\rho##Av i know that m1 = m2 + m3 since there are no dimensions I am assuming that areas are the same everywhere, density does not change therefore velocities...

Homework Statement Hi, I do not know how to resolve question 1d and 2d at all. I hope the rest is well resolved, not sure about 1c and 2c. Can someone check my work and help me resolve problem with this questions, please? Task A hammer of mass 1700kg is dropped 2.5m under its own in fluency of...

Homework Statement Find the 2 unknown variables.[/B]Homework Equations Am I doing this right? Can someone help me find the solution?[/B] The Attempt at a Solution To compute for the velocity of the target/arrow combination immediately after the collision: M_bV_{bi}=M_bV_{bf}+M_wV_{wf}...

Homework Statement On a frictionless, horizontal air table, puck A (with mass 0.250 kg ) is moving toward puck B (with mass 0.360 kg ), that is initially at rest. After the collision, puck A has a velocity of 0.125 m/s to the left, and puck B has velocity 0.655 m/s to the right. I already...

Homework Statement Homework Equations p=mv K=(1/2)mv2 Integration and Derivation Methods J=mΔv The Attempt at a Solution So far I set Pbefore=(Δm*u)+(MVcar), with Vcar depending on the time that has passed (I'm not sure how I should find the function for Vcar(t). For Pafter I included the...

how do you describe the speed of an object in momentum space (energy, momentum as the 2 axes) where there is no distance or time? Can you give an example?

Do protons' inherent gyroscopic nature produce progressive ripples in the electromagnetic field? If so, then is there an ensemble of transverse electromagnetic undulations arising from the proton's angular momentum that contribute to electronic orbital energy in, say, a hydrogen atom? If these...

Homework Statement C14 disintegrates by b-emission with a reaction energy (q value) of 0.155 MeV. A b-particles with an energy of 0.025MeV is emitted in a direction at 135° to the direction of motion of the recoil nucleus. Then the momenta of the three particles (b = V, 14N) involved in this...

Hi all Can anyone please help me with Q14 (attached) as you can see I am getting 167000N however the correct answer is 83000N Many thanks ZanyZoya

Homework Statement A jumper departs from an inclined plane with a velocity of 100km/h and no rotation. He wants to summersault while he is airborne within 2s.Based on the conservation of angular momentum, he will start tom rotate if his wheel's rotation is slowed down. His wheels are hollow...

Can momentum space also able to handle spin and polarizations? I'm understanding it that in QM, you have position, momentum, spin, polarization as observables. Position and momentum can be equivalent via Fourier transform. So if you use momentum space instead of position, how do you handle...

HI In a new report published the Thursday 26 October in the journal Science Advances, a team of physicists based in the UK, Germany, New Zealand and Canada describe how new research into "optical angular momentum" (OAM) could overcome current difficulties with using twisted light across open...

Homework Statement Two beads with masses of M and m are threaded on a vertical loop with radius of R. M is released without velocity from a height of 1.5R from the bottom of the loop. The collision between the beads is completely elastic. What is the smallest mass M that will make the second...

Homework Statement Everything we know is in the picture. There is no friction between the body and the wagon and between the wagon and the floor. What will be the maximum height that the body will reach on the wagon? (Answer:0.008v02) What will be the velocities of the body and the wagon once...

Homework Statement Two balls with mass m and 4m collide at the location x=y=0 and stick. Their initial velocities just before the collision can be represented as v1=(i+j) v and v2=(j-i)v' respectively. Their final velocity vf makes an angle θ with the +x axis. Find v and v' in terms of vf and...

I read that kinetic energy may not be preserved, but momentum must always be preserved. How can that be? If there's a loss in kinetic energy due to friction or heat, the velocities will be reduced thus momentum will be reduced?

I am working through Lessons in Particle Physics by Luis Anchordoqui and Francis Halzen; the link is https://arxiv.org/PS_cache/arxiv/pdf/0906/0906.1271v2.pdf. I am on page 11, equation 1.3.20. The authors have defined an operator ##L_{\mu\nu} = i( x_\mu \partial \nu - x_\nu \partial \mu)##...

Homework Statement The dwarf planet Pluto orbits very ellipticaly... Pluto's nearest (perihelion) and farthest (apihelion) distances from the Sun are 30 AU and 50 AU, respectively. (One AU or Astronomical Unit=the mean distance from the center of the Earth to Astronomical Unit = the mean...

Homework Statement A taxi car weighing 2000kg hits a stationary mini-van that has a mass of 2200kg. The taxi stops and the mini-van rolls and hits a stationary sports car with a mass of 1830kg. Their bumbers hit and they move together at 2.3m/s. What is the velocity of the taxi before the...

Homework Statement Derive, using the canonical commutation relation of the position space representation of the fields φ(x) and π(y), the corresponding commutation relation in momentum space.Homework Equations [φ(x), π(y)] = iδ3(x-y) My Fourier transforms are defined by: $$ φ^*(\vec p)=\int...

Hi all, I have the following query: I understand that the "make-up" of momentum probability density ##|\tilde{\Psi}|^2## has an effect on the motion of the spatial probability density ##|\Psi|^2##. For example, a Gaussian ##|\tilde{\Psi}|^2## centred far to the right will cause ##|\Psi|^2## to...

Homework Statement We release a ball from a height h and it bounces for a time t. What is the value of k (the quotient of the ball's momentum before and after collision with the ground)? Homework EquationsThe Attempt at a Solution I'm kind of lost here. :/ [/B]

Homework Statement A 10 g bullet traveling at 400 m/s strikes a 10 kg , 1.2-m-wide door at the edge opposite the hinge. The bullet embeds itself in the door, causing the door to swing open. What is the angular velocity of the door immediately after impact? Homework Equations p[/B]= mv L = Iω...

Homework Statement A comet orbits the sun. It's position in polar coordinates is given by, $$r(\phi)=\frac{1.8r_0}{1+0.8\cos{\phi}},$$ where ##r_0## is the position at closest approach. Its velocity at this point is given by ##v_0##. Use the concept of angular momentum to find the following...

Homework Statement A cylindrical rocket of diameter 2R and mass M is coasting through empty space with speed v0 when it encounters an interstellar cloud. The number density of particles in the cloud is N particles/m^3. Each particle has mass m << M, and they are initially at rest. Assume each...