Collisions Definition and 724 Threads

  1. Quarlep

    Can Feynman Diagrams Show How Protons Can Collide Despite Pauli's Principle?

    I learned that Pauli principle says two fermions cannot be same place than how we can collide two protons actually its also impossible (for me) to show this in feymann diagram.I want to know how its possible. Thanks
  2. L

    Deriving Orbital Motion from Collisions in Travel along Chords

    Homework Statement Inscribe N chords of equal length within a circle of radius r. A body of mass m travels at constant speed v along the chords and is perfectly reflected in each collision with the circle (there is no momentum change tangent to the circle). Show that the radial momentum change...
  3. J

    Finding Displacement in a Box Collision with Coefficient of Restitution

    Homework Statement A cubical box of mass 10 kg with edge length 5 m is free to move on a frictionless horizontal surface. Inside is a small block of mass 2 kg, which moves without friction inside the box. At time t = 0, the block is moving with velocity 5 m/s directly towards one of the...
  4. G

    When are temperature effects included in collisions?

    When a proton collides with a proton say at the LHC, is vacuum field theory used? It seems like you shouldn't have to include temperature effects since there are only two particles. But then again, all experiments take place at finite temperature, the ambient temperature of the room? When a...
  5. A

    Conservation of momentum in perfect elastic collisions

    I learned that momentum conservation is vectorial, and now, when i read about perfect elastic collisions, I can't understand why they use a scalar conservation. I tryed to use vectorial coervation to see the diference and it's true: it's needed a scalar conservation. But why?
  6. S

    How Do Speeds Change After an Elastic Collision?

    Ball A, a 0.055 kg ball, moving with a speed of 2.50 m/s collides head-on with ball B, a 0.095 kg ball initially moving away from it at a speed of 1.15 m/s. Assume a perfectly elastic collision. Take the initial velocity of ball A to be in the positive x direction. (A) What is the speed of...
  7. A

    Collisions - bullet shot in in block

    Three blocks (1,2,3) of mass 3.00 kg, 2.00 kg, 1.00 kg sit linearly 10.0 cm apart from each other on a frictionless surface. A 25 g bullet is shot at the first block, it travels through the first block, and embeds itself into the second block (without falling over) which then collides into...
  8. Saitama

    Projectile motion collisions problem

    Homework Statement I don't have the exact problem statement but I remember the important data. I have to find the value of ##x## in the figure such that the projectile reaches to its original position. The initial speed is ##20\sqrt{2}\,m/s## at an angle of ##45^{\circ}## with the...
  9. M

    W+ or W- in neutrino collisions

    All the Feynman diagrams I have seen so far for a neutron colliding with a neutrino have a w+ with an arrow from the neutrino to the neutron. Would it not also be possible with a W- leaving the neutron taking away negative charge for it to become a positive proton or is there some quantum rule...
  10. P

    Collisions in rotational dynamics

    If I have say a stationary rod, and a particle collides with the rod whilst moving at speed v at the top end, why does the rod then proceed to rotate about the centre of mass of the system (whether that be in an elastic or completely inelastic collision where they both stick together). I...
  11. jdawg

    Momentum and kinetic energy in collisions with a bullet

    Homework Statement A bullet of mass 4.2 g strikes a ballistic pendulum of mass 2.0 kg. The center of mass of the pendulum rises a vertical distance of 18 cm. Assuming that the bullet remains embedded in the pendulum, calculate the bullet's initial speed. Homework Equations The...
  12. icesalmon

    How Is Energy Lost in Elastic vs. Inelastic Collisions?

    Homework Statement I was asked to compare the energy loss of a system of two boxes moving towards each other, colliding elastically and in-elastically in two different situations that are not influenced by friction. There are no springs attached to either massThe Attempt at a Solution I...
  13. M

    Inelastic collisions - conservation of energy

    Homework Statement Homework Equations K = E + U E = 1/2mv^2 U = mgh The Attempt at a Solution So I think that for a, half the final velocity of m is equal to the initial velocity of 2m. So that's v = sqrt(2gr)/2? Momentum is not conserved because normal force and gravity are...
  14. M

    Method for unique collisions between 2 subdivided ellipses

    Hello, I would like find a way to figure out how many unique collision there are between 2 equally subdivided ellipsoids (velocity=1). When you have 2 ellipsoids and you let them collide than you have an infinite amount of possible outcomes. The goal is to reduce this infinite number to...
  15. S

    Collisions, Impulse, and Reference Frames

    A racquet ball with mass m = 0.245 kg is moving toward the wall at v = 15.4 m/s and at an angle of θ = 28° with respect to the horizontal. The ball makes a perfectly elastic collision with the solid, frictionless wall and rebounds at the same angle with respect to the horizontal. The ball is in...
  16. L

    Collisions: Elastic vs inelastic

    So there are a bunch of assignments in physics built on the conservation of momentum law where a bullet of some mass, hits a target of some mass, neglecting friction find the velocity at which the target starts moving. That is all very simple in case of an inelastic collision, all the energy of...
  17. L

    Have Quark Collision Experiments Revealed the Nature of Matter?

    Hello to all. I have a pretty general question. Hopefully it will require a somewhat technical answer. My question is this. Has there been any experiment where quarks have been smashed together? Perhaps at the lHC or Fermi. The other day I was told about such an experiment where two quarks were...
  18. A

    How do I calculate the number of collisions per unit area in an ideal gas?

    I an ideal gas how do I calculate the number of collision per unit area? By collision I do not mean collision between the atoms but rather it is a problem where I know that a nucleation cluster of area A is in my gas, and I want to find the probability that it will get hit by an atom. I know the...
  19. P

    Would modeling collisions using Coulomb forces be useful?

    Hi, I am trying to decide on a topic for my senior project, and my professor and I fleetingly discussed my idea of writing a program that models collisions of macroscopic objects using the mutual repulsive forces of their valence electrons rather than standard conservation laws. My question is...
  20. P

    Analyzing 2D Elastic Collisions with Varying Masses and Velocities

    Homework Statement A 1.0-kg particle is moving in the +x direction at 4.0m/s when it collides elastically with a 4.0-kg particle moving in the −x direction at 1.0m/s After colliding the 1-kg particle moves off at 130 counterclockwise from the positive x-axis. Find the final speeds of both...
  21. X

    Elastic and Inelastic Collisions

    Homework Statement http://i.imgur.com/c5pOIe8.png & http://i.imgur.com/zdxfXLE.png Sitting in a parking lot you witness a minor, but still noteworthy collision between two cars. You wondered, "Is momentum really conserved in collisions?" It didn't seem like it was in the real world so...
  22. R

    Zero Momentum in Elastic Collisions

    Is it possible to have a zero vector? The question arises in the context of conservation of momentum. In center of mass reference frame, the momentum of two masses involved in an elastic collision is zero before (as well as after) collision. It is because the two masses have equal and oppposite...
  23. ryanuser

    Photon Collisions: Do They Bounce or Pass Through?

    Do photons bounce off after they hit each other or they just pass through one and another?
  24. Simon Bridge

    Rod Cross' collisions, sports balls, and silly putty

    A surprising find looking for something else: http://www.physics.usyd.edu.au/~cross/ Somewhat extensive notes on various small-ball sports physics - including material on collision physics and a neat vid of a falling slinky. I've mined: Ball bounce for comparative data for experiments...
  25. H

    What's left over after particle collisions, like LHC?

    I'm curious to know what tends to be 'left over' after particle collisions at sites like LHC. I realize that many different particles may arise, depending on the types of particles used for collision, as well as the kinetic energy put into the experiments. Despite the amazing diversity of...
  26. B

    Solving Elastic Collisions - Momentum & Final Velocity

    Please clear up this problem... Mass 1 = 8 kg, and v = 3 m/s to the right. Mass 2 = 4 kg, and v = -3 m/s to the left. Both objects are on the same x-plane. Totally elastic collision. Momentum of mass 1 is 24, and momentum of mass 2 is -12. How do I determine final momentum for each...
  27. K

    Solving Elastic Collisions: 25g & 10g Objects

    Homework Statement A 25g object moving to the right at 20cm/s overtakes and collides elastically with a 10g object moving in the same direction at 15 cm/s. Find the velocity of each object after the collision Homework Equations Ʃp=Ʃp' v1+v1'=v2+v2' The Attempt at a Solution First...
  28. A

    Drude Model: Electrons & Collisions

    As far as I understand: In the Drude model we take the electron to be moving in a random direction after each collision (*), such that the mean velocity is simply the average of -eEt/m, which is just -eEτ/m, where τ is the relaxation time. But I am very confused about this basic assumption...
  29. Crusader711

    Conservation of Momentum- Inelastic Collisions

    1. This was a hard test question that I took partial credit on. I want to fully understand what I did wrong so that I’m fluid with the concept. I’m also new to this forum. I love constructive criticism too! lol Zombie Apocalypse has arrived and the war has begun. Your task as a physics student...
  30. C

    One Dimensional Collisions: Analyzing Impulse and Average Forces

    Homework Statement a ball of mass 2.50kg is thrown upward. it leaves the hand w/ an upward velocity of 19.6m/s. (on the way down now )after the ball hits the throwers hand it comes to rest in .20s a. What is the impulse exerted on the ball? b. What is the average net force on the ball...
  31. W

    Why Does Toilet Water Splash Back Up?

    Now although this is silly and quite crude (You have been warned), it is a legitimate physics question. I was sitting on the toilet a few days ago and I got some splash back. I started thinking about elastic collisions and how no matter what, nothing is perfectly elastic (correct?). Why would...
  32. A

    Collisions Of Two Asteroids in the Main Asteroid Belt.

    Homework Statement If there are two asteroids A and B of equal mass (and density of 3000kg/m^3), with the same semi major axis of a=2.2 AU with asteroid A having a circular orbit and no inclination, and asteroid B has an elliptical orbit with an eccentricity of e=0.05 and an inclination of...
  33. P

    Watch a Fascinating Demo of Collisions Inside a Conductor

    I remember seeing a demo of collisions inside a conductor. It was a long board with nails representing the atom positions (a square lattice arrangement) and you would put a hand full of marbles at the top. The marbles will slide down but since they keep hitting the nails the velocity will be...
  34. J

    Exercise on collisions and oscillations

    Hi, I tried to solve this problem myself and I'd like someone to check it :) Thanks already! A ball is rolling towards a block, which is connected to a spring. Assume no friction occurs. The initial velocity of the ball is 10 m/s. The spring constant is k = 5 N/m. Mass of the ball = 5 kg and...
  35. E

    Some questions about Hard-sphere Maxwellian Gas Collisions

    Consider a unit volume (rigid walled container of surface area S) containing N molecules with diameter d, having a maxwellian speed distribution with a mean time between collisions t*. Allowing for a stable (i.e constant) equilibrium mono-layer distribution of some number of these molecules...
  36. S

    Inelastic collisions in 2 dimensions

    I am unsure how to proceed with this problem because it is asking for the final velocity of one of the two objects given the initial velocities. This is an inelastic collision not a completely inelastic collision, which means the two objects do not stick together. The book makes a distinction...
  37. O

    Elastic vs inelastic collisions formulas

    When doing practice problems from my textbook, I often get confused with both of them. MOre specifically there are usually formulas which pertain to only one of those types of collisions. Ex: (v_1-v_2)_i = -(v_1-v_2)_f Does anyone know more of these types of formulas, or tricks to...
  38. W

    Direct Collisions with objects moving in towards each other

    Homework Statement Two Smooth spheres of masses m and 3m move with speeds u and v in opposite directions. The smaller mass is brought to rest. (i) show that the coefficient of restitution,e, is given by e =(u - 3v)/(3u + 3v) (ii) show that u ≥ 3v Homework Equations m1u1 + m2u2 =...
  39. W

    Direct collisions on an inclined plane

    Homework Statement A smooth sphere falls vertically and strikes a fixed smooth plane inclined at an angle of ∅ to the horizontal.If the coefficient of restitution is (2/3) and the sphere rebounds horizontally, Its speed before impact is u and after impact v calculate the fraction of kinetic...
  40. V

    Why do collisions cause more pain than forced movement?

    So this question I have is so obvious that it's probably not even worth talking about from a scientific point of view but I just can't keep it out of my head. The moderators are welcome to delete this if they think it's too silly. Suppose there is a person tied to the windshield of a car. When...
  41. U

    What Happens If a Craft Travels Through a Wormhole and Collides with a Planet?

    Question: If one creates a wormhole (theoretically has a space/hyper drive) and one is going from point A to point B, and there is a moon or planet in the way, intersecting the path... What might happen? Is a wormhole out of space/time of this dimension and thus the craft would pass through...
  42. X

    Conservation of Momentum and Kinetic Energy in Inelastic Collisions

    Homework Statement A 50g object is moving east at 0.3 m/s. A 100g object is moving east as well at 0.25 m/s. These objects have an inelastic collision. a) Find their final velocity b) Find the kinetic energy lostHomework Equations P1 + P2 = P3 + P4 ; momentum is conserved Ek = 1/2 mv^2The...
  43. U

    Relativistic collisions - different frames, threshold energy

    Homework Statement (a) Show that E2 - p2c2 is a Lorentz invariant, where E is the total energy, p is the momentum, c is speed of light. (b) In the lab frame, an utlra-relativistic electron with γ = 100 collides head-on with a photon of energy E. Find the threshold energy E required to...
  44. T

    Physical effects of car collisions on metals

    Trying to understand what happens upon impact to the metal of a car that is stopped (Vehicle 1)when another car's driver's side rear (Vehicle 2) impacts the stationary car . Vehicle 2 is a heavier, larger car and is moving in reverse at approximately 10-15 MPH. The impact site on Vehicle 1 is...
  45. Z

    Collisions between two balls in 2d-motion

    Homework Statement A ball A is dropped from rest from a height of 2.0 m above the floor. Meanwhile that ball A is released, an other ball B is pushed away with the starting speed v_0 from the position shown in Figure. Which angle α is needed for B to collide with ball A? Homework...
  46. xatu

    Kinetic Theory of Gases: Effusion and Collisions

    Question: In the following link I'm concerned with only pages 1 and 2. I'm wondering if there is a typo or an error of some kind. I feel like there is some inconsistency to what the author refers to as \upsilon, \theta, and \phi. The only angle shown in the diagram is \upsilon, which is the...
  47. S

    Boyle's Law and collisions by the ideal gas molecules on the container

    When we use Boyle's Law it means that as pressure increases the volume of the container would decrease. In my notes they stated that if I were to halve the volume there would be two times the number of collisions per second which implies that the force exerted is doubled. But why is this so? I...
  48. C

    MHB Collisions and loss of kinetic energy

    Could someone please check my answers so far for this question as its getting very messy so I'm not sure if I've made a mistake :/ Two particles of masses 2m and m are moving along the x−axis with constant velocities u1i and u2i respectively...
  49. B

    What is the rigorous proof for elastic collisions?

    Suppose that a mass M1 is moving with speed V1 and collides with mass M2 which is initially at rest. After the elastic collision they make, both momentum and kinetic energy are conserved. m_{1}v_{1f} + m_{2}v_{2f} = m_{1}v_{1i} \frac{1}{2}m_{1}||v_{1i}||^{2}=...
  50. X

    Solving 2D Collisions: Find the Velocity of Eight Ball After Impact

    Homework Statement In a game of billiards the 0.165 kg cue ball is hit toward the 0.155 kg eight ball which is stationary. The cue ball travels at a speed of 6.2 m/s and after impact rolls away at an angle of 40.0 degrees counterclockwise from its initial direction with a velocity of 3.7 m/s...
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