Momentum conservation Definition and 241 Threads

I would like to preface this by saying that I do not in any way resemble a physicist - and I'm sure the crudeness of my work will confirm that, but I thought that this was so cool, I wanted to share it. I'm just a follower of physics. I understand that some of the concepts I'm going to be...

Homework Statement Question - Models of global warming predict that large sections of the polar ice caps will melt. Explain what effect this will have on the rotation of the Earth, however slight. Homework Equations L = Iw The Attempt at a Solution Assuming polar ice caps protrude the earth...

Homework Statement Consider a massless rod of length $L$ with a small mass $m1$ attached on one end, and $m2$ attached on the other end. The rod is initially in the vertical position at rest on a frictionless surface, with $m1$ on bottom and $m2$ on top. A small impulse is applied to the top...

Homework Statement Three blocks of identical mass are placed on a frictionless table as shown. The center block is at rest, whereas the other two blocks are moving directly towards it at identical speeds v. The center block is initially closer to the left block than the right one. All motion...

Homework Statement A 2.0 kg ball moving with a speed of 3.0 m/s hits, elastically, an identical stationary ball. If the first ball moves away with angle 30° to the original path, determine: a. the speed of the first ball after the collision. b. the speed and direction of the second ball after...

Homework Statement A solid sphere is set into motion on a rough horizontal surface with a linear speed v in the forward direction and angular speed v/r in the anticlockwise direction. Find the linear speed of the sphere when: a) When it stops rotating b) when slipping ceases Homework...

Homework Statement [/B] A block of mass m is attached to a spring with a force constant k, as in the above diagram. Initially, the spring is compressed a distancex from the equilibrium and the block is held at rest. Another block, of mass 2m, is placed a distance x/2 from the equilibrium as...

Homework Statement The white ball in the figure has a speed of 1.81 m/s and the yellow ball is at rest prior to an elastic glancing collision. After the collision the white ball has a speed of 1.37 m/s. To the nearest tenth of a degree, measured counterclockwise from east, what angle does it...

Dear Experts, Total momentum of a system is said to be conserved in perfectly inelastic collisions also. I have a slight problem trying to comprehend a simple example regarding the same. If a small mass 'm' , say a ball is thrown at a huge stationary mass 'M' , say a wall. If the collision is...

Take the case of Atwood machine, Where the masses of blocks are m and m,now,another ball of mass m strikes one of the blocks with a speed v and sticks to it. Considering our system as blocks+ball+string connecting the blocks(no pulley),can we apply conservation of momentum? Please explain...

Homework Statement A car of mass 1500kg is parked on a 30degree slope before rolling down a distance of 30m onto a flat section where it collides with a stationary car. The cars stick together and scrape along the road for 20m until they come to a rest. Calculate the velocity of the two...

The question is: When a large car collides with a small car, which one undergoes the greater change in momentum: the large one or the small one? Or is it the same for both? I wanted to plug in dumb numbers: m_tv_{ti} + m_cv_{ci} = m_tv_{tf} + m_cv_{cf} lets assume the truck has a mass of...

Compute the force exerted on the palm of you hand by the beam from a 1.0W flashlight. (a) if your hand absorbs the light, and (b) if the light reflects from your hand. What would the mass of the particle that exerts that same force in each case would be if you hold it at Earth's surface? On...

Homework Statement A child with mass m is standing at the edge of a merry go round having moment of inertia I, radius R and initial angular velocity x as shown. (The figure shows a disc moving anticlockwise, with the velocity v (Mentioned at the end) pointing upwards to the right most edge of...

One of the possible decay modes of the neutral kaon is ## K^0 \rightarrow \pi^+ + \pi^- ## The rest masses of the K0 and pion are 498 MeV/c2 and 135 MeV/c2, respectively. In 2-dimensions (xz-plane), if the kaon has an initial momentum of 2000 MeV/c in the z direction, what is the momentum of...

Homework Statement A flywheel and shaft have a moment of inertia of 600kg and is rotating at 5 rev/s. Another flywheel and shaft, on the same axis, is suddenly connected by means of a clutch. If this flywheel and shaft has a moment of inertia of 620kg and is initially at rest, calculate: a)...

Homework Statement A 2.0 kg ball moving with a speed of 3.0 m/s hits, elastically, an identical stationary ball. If the first ball moves away with angle 30° to the original path, determine: a. the speed of the first ball after the collision. b. the speed and direction of the second ball after...

Homework Statement Can you change the system (as you would in a work/energy problem) so you can get rid of all external forces in a momentum problem for example by making your system the earth, a mass, and a spring (if the problem involved those 3 objects)? Homework Equations P=mv[/B]The...

Homework Statement A 2 kg frictionless cart with a velocity of 6 m/s hits a wall and rebounds with a velocity of 4 m/s. What is the impulse on the cart by the wall? Is momentum conserved? Homework Equations J = Δp The Attempt at a Solution J = Δp = pf-pi = mvf-mvi = 2kg (-4m/s -6m/s) = -20...

Consider the flat FRW metric in Cartesian spatial co-moving co-ordinates: ##ds^2=-dt^2+a(t)^2(dx^2+dy^2+dz^2)## As I understand it, since the metric does not depend on the the spatial co-ordinates, there exist Killing vectors in the ##x##,##y##,##z## directions. Does this imply that the...

I was hoping to get a more complete understanding how a Venturi vacuum increases the Momentum of the fluid. I know Momentum is an awful way to pose this question but it really is important that it can be explained by momentum instead of conservation - Hence the post. An initial pressure...

Question with diagram: Relevant equations: Attempt : My question: Using my method I got the wrong force , not sure if in this situation I can use Q=A1U1 = A2U2, hence maybe that's why U2 = 195 m/s looks wrong/too fast? I continue to use momentum conservation in the x and y directions...

Suppose we take the three Newton’s Laws as axioms. Existence of inertial reference frames F = ma F(A on B) = -F(B on A) Also suppose also we are considering purely classical mechanical processes on point particles (no heat transfer, etc.). It is clear to me that the conservation of momentum...

Homework Statement A block of mass m1 slides along a frictionless table to the right with a speed of v1. A second mass M2 slides in the same direction with a speed of v2 such that it will collide with m1 which is in front of m2. Say that a spring of stiffness k is attached to one of the masses...

Homework Statement In the pictures Homework Equations Fnet = dp/dt The Attempt at a Solution I know in part b there is a net external force (gravity) that does positive work, fnet > 0, thus dp/dt is positive. Does the spring in part c increase or decrease the momentum of the system? I am...

Hey guys, I need help with conserving momentum at these vertices (this is Bhabha scattering): So in Diagram (a), the first vertext to the left. The incoming momenta are p_{1}+p_{2}. The outgoing momentum I'll call it p. So...shouldnt I have p_{1}+p_{2}=p? Furthermore, is the propagator...

1. The problem statement, all variables and given/own data http://prntscr.com/661d5d Homework Equations m1v1 + m2v2 = m1v1p +m2v2p The Attempt at a Solution I asumed that the momentum in the y direction is constant, and that in the x direction it is conversved. Also, i thought of it as 2 parts...

Homework Statement a) Particle A decays at rest into two photons. Calculate, in terms of the rest mass of A, the energy and momentum of each photon. b) In a different reference frame, particle A is initially in motion such that its kinetic energy is equal to its rest energy. Find the momentum...

Let ##L(\vec{r},\dot{\vec{r}})## be the lagrangian function, usually to get angular momentum conservation one impose ##\delta L=0## and form there we get ##\sum \vec{r}\wedge m\vec{v}=const##. There is however a conceptual problem with this procedure related to the fact that invariance under...

Homework Statement Suppose, a rod of negligible mass has two balls(A & B) at its two ends. Both the balls have same mass m. The rod is rotating around its center C with a uniform angular velocity ##\omega##. Another ball D (mass M) has a velocity v. At some time, A and D collide with each...

< Mentor Note -- thread moved to HH from the technical physics forums, so no HH Template is shown > So the problem that I have been assigned has formulas of rotational energy, momentum, trajectories, inertia, and inclined planes. A solid sphere is rolling down an inclined plane (that is placed...

Hello, I recently posted a few conceptual questions regarding conservation of momentum. I'm processing the information more easily now, but I've hit yet another bump in the road. I've learned that in an inelastic collision in which "velocity is the same before and after the collision" the...

One thing that's been troubling me lately is the idea that a quantum experiment can start with the same initial conditions, but the outcome is probabilistic, not deterministic, and how this fits in with the conservation of momentum. I was thinking about the classic double-slit experiment, in...

Homework Statement A person stands on a platform, initially at rest, that can rotate freely without friction. The moment of inertia of the person plus the platform is IP. The person holds a spinning bicycle wheel with its axis horizontal. The wheel has a moment of inertia Iw and angular...

Homework Statement m1= 3kg m2= 6kg v1 = 5m/s v2= 2m/s d = 3m DIAGRAM : http://gyazo.com/17b3126726b109256a35f65b86708bb0 Homework Equations Conservation of momentum: m1+v1 = m1v1'+m2v2' Conservation of elastic: m1v1^2+m2v2^2 = m1v1'^2+m2v2'^2 The Attempt at a Solution Now my attempt...

Homework Statement A possible decay mode a of a positive Kaon in the production of three Pions as shown below:. K+ → π+ + π+ + π− Whats is the maximum Kinetic energy that anyone of the pions can have? The kaon is a rest when...

Homework Statement Prove $$ j^{\mu} = j_ {EXTERIOR}^{\mu} + j_ {INTERIOR}^{\mu}$$. Writing $$j_ {EXTERIOR}^{\mu}$$ in terms of the energy-momentum tensor. Prove $$j_ {EXTERIOR}^{\mu}$$ is related to the Orbital Momentum and $$j_ {INTERIOR}^{\mu}$$ to the spin.Sorry, for the lane shifts...

Homework Statement Two objects of equal mass traveling toward each other with equal speeds undergo a head on collision. Which one of the following statements concerning their velocities after the collision is necessarily true? (a) They will exchange velocities. (d) Their velocities will...

Homework Statement Good morning/ afternoon I have a doubt about relativistic collisions, any help will be welcome. Consider the process of annihilation electron-positron to two photons. Calculate in the centre of mass system the wavelength of photons produced using momentum of e+e-...

I am trying to follow this solution but I can't see how the momentum p is equivalent to the sqrt(T^2+2Tmc^2) I get that T=p^2/2m which yields p=sqrt(2mT) but why is there a T^2 term...??

I have always been under the impression that Newton's third law and the law of conservation of linear momentum are really the same thing; synonymous, so to speak. But then I was wondering if Newton's Third Law holds for a non-isolated system. I mean, I know for sure that momentum conservation is...

Homework Statement A ball of mass m travels with speed v, hits a stationary ball with the same mass m and after collision they both move at speed v/2. From the point of view of the first ball the total momentum is -mv and after the collision it is 0. why isn't the law of conservation of...

Mechanical energy is conserved whenever momentum is conserved. T/F? My guess is true: If momentum is conserved, no external forces are applied on the system. Hence mechanical energy can't change! (No change in PE, no change in KE). BUT: My answer booklet says FALSE! Why?

Homework Statement Hello, guys. I'm not a native english speaker, so don't mind if I wrote something incorrectly (if you find any error or difficulty in what I wrote just inform me, please). A little ball is hold by a thread of negligible mass which moves round a vertical axis with constant...

I understand that Feynman diagrams can be expressed either in the position or momentum representation. Is the 4-momentum conserved at the vertices in each case or only in the momentum representation?

Homework Statement Two hobos each of mass m_h , are standing at one of a stationary railroad flatcar with frictionless wheels and mass m_c . Either hobo can run to the other end of the flatcar and jump off with the same speed u relative to the car. a) use conservation of momentum to find...

In an indirect transition from the valence band maximum to conduction band minimum, the momentum of electron and hole would not change but the crystal momentum would change and this change is supplied by phonons.I have two questions here: 1) phonons don't carry momentum so how they can transfer...

Homework Statement Explain why a soldier holding the machine gun will experience a force from the gun whilst it is firing bullets Homework Equations Momentum is always conserved in closed systems F= Δmv/Δt The Attempt at a Solution The system has zero momentum then when the...

When a transition from valence band to conduction band happens (in a direct-gap material), how the momentum is conserved while the group velocity of electron is changed considerably?

I was thinking about one of the many resolutions of the so-called 'twin paradox' within SR framework. I realize many methods of resolving this have been proposed, but I am curious about the particular solution that uses 'acceleration' of the traveling twin, to create the required asymmetry for...