Collision Definition and 1000 Threads

  1. jeff einstein

    Ambiguous question on momentum and how it works...

    A question states that a ball with a mass of 5 kg and a velocity of 10 m/s collides with a stationary wall. The question then asks for the momentum of the ball after the collision. No other information is given. This is a rather ambiguous question, as it doesn't provide the time taken for the...
  2. S

    Find speed of CoM after collision between ball and "square structure"

    (a) $$\bar x=\frac{\int_{0}^{L} \frac{\alpha_o}{L}x^2dx}{\int_{0}^{L}\frac{\alpha_o}{L}xdx}$$ $$=\frac{2}{3}L$$ (b) $$x=\frac{x_1+x_2}{2}=\frac{1}{6}L$$ $$y=\frac{y_1+y_2}{2}=\frac{1}{3}L$$ (c) I am not sure about this part. Do I need to divide the conservation of momentum into two...
  3. T

    A Entropy increase in proton/proton collision?

    Does entropy increase when two protons collide at moderate velocity? Is momentum of one fully transferred to the other. Is the vector coming in more certain than the vector going out after the event. I guess the answer might invoke the uncertainty principle but is there some certainty with...
  4. someone_2156

    Time taken for a planet to collide with the Sun

    TL;DR Summary: if a planet was suddenly stopped in its orbit, suppose to be circular, find how much time will it take in falling onto the sun(in terms of time period) I know that T=2pi (r^3/GM)^1/2 and a=GM/x^2 how to proceed further
  5. DaveC426913

    I Galaxy collision separates dark matter from regular matter

    "... the gas between the galaxies collided, becoming turbulent and superheated. While both dark and normal matter are influenced by gravity, the normal matter also interacts via electromagnetism, which slowed it down during the collision. Consequently, the dark matter moved ahead, decoupling...
  6. Heisenberg7

    Is Linear Momentum Conserved in This Case? (sliding box hits a floor tile)

    Hello, I actually solved this problem using conservation of angular momentum, but I was wondering if linear momentum is conserved. Here's my thought process: (block + tile system) The block is going to hit the tile with some force ##\vec{F}##. Due to the Newton's third law, that force is also...
  7. A

    B Is this an Unavoidable Collision between 2 spaceships traveling at 0.6c each?

    Relativity always talks in terms of observer but fail to explain common sense problems like this. The fact that no one can measure anything faster than light does not preclude to objects moving towards each other at a higher velocity than an external observer can measure. Move the observer to...
  8. I_Try_Math

    Finding speed of two billiard balls in elastic collision

    ## \vec{v_{1i}} = \langle 2.2, -0.4 \rangle ## ## \vec{v_{2i}} = \langle -1.4, 2.4 \rangle ## Let ##\theta## and ##\phi## be the angles made by ##\vec{v_{1i}}## and ##\vec{v_{2i}}## with the x axis, respectively. Let ##\theta'## and ##\phi'## be the angles made by ##\vec{v_{1f}}## and...
  9. I_Try_Math

    Deriving speed equations | Elastic collision

    So far I've got: ##p_{1,i} + p_{2,i} = p_{1,f} + p_{2,f}## ##p_{1,i} + 0 = p_{1,f} + p_{2,f}## ##m_1v_{1,i} = m_1v_{1,f} + m_2v_{2,f}## According to the textbook, the final speeds should be written in terms of ##v_{1,i}, m_1, and m_2##. It looks like I need another way to relate everything...
  10. T

    Impulse and perfectly inelastic collision between 2 points

    The main thing about this problem is to find the components of the velocity, ##v_{A+B}##. To do that you have to use the conservation of linear momentum of the collision. In this case, since there is an impulse, I should have ##\Delta P = J##. But the impulse is given prior to the collision...
  11. rocketwaveuk

    I Matter Anti-Matter Annihilation

    The pure energy coming from a collision and how is it measured or is it just "A Formula" and is any of that energy Dark Energy or even Dark Matter, the reason for the question is because the Dark Energy/Matter vs normal Energy/Matter seems to align with what is seen now after the Big Bang...
  12. Bling Fizikst

    Speed of charged balls after collision

    I tried to apply energy conservation . $$\frac{-kQq}{l}=\frac{m}{2}(v_1^2+v_2^2)-\frac{kqQ}{2r}$$ Now conserving momentum : $$0=mv_1-mv_2$$ Solving for ##v_1=v_2=v'## we get : $$v'=\sqrt{\frac{kQq}{m}\left(\frac{l-2r}{2r}\right)}$$ Since the balls are elastic , so they should collide...
  13. I

    B How to determine applied force when two objects collide? (basic physics engine)

    I'm trying to make a very basic physics engine. So far I've got a variety of small things worked out but I've been driving myself crazy trying to work out collisions. From one sense I get I can use momentum and impulse to determine the velocity of an object after a fully elastic collision (no...
  14. S

    B Electron's movement after getting hit by a photon that bounces at 90 degrees

    I just started studying Quantum physics and i'm learning about Comptonspreading and I have this question in my book that I don't completely understand So if an electron is standing still, then it gets hit by a photon moving in a straight line into the electron. The photon then bounces off the...
  15. billtodd

    Inelastic collision of two squares

    I know that the speed of the centre of mass is ##v_{cm}=(mv_0+mv_0)/(2m)=v_0##. But I don't know how to proceed from here with the angular speed around the centre of mass of the system. Any help will be appreciated.
  16. P

    When does Phobos collide with Mars?

    I tried to calculate it, but I think I'm going wrong way. I found m^2/s^2 in the definite integral... (170539114.487m^2/s^2) I don't know what it means!!
  17. S

    Can Two Particles Have Multiple Collisions in a Single Interaction?

    I am stuck with this problem. Intuition tells me the answer is no, but I am struggling to prove it. If we consider two particles travelling in the same direction, the 2nd particle will gain velocity (impulse is in same direction to velocity), and the first particle will lose velocity (if it...
  18. S

    Fast and Furious Scene Analysis

    The collision seems to be an inelastic collision meaning momentum is conserved however, energy is not due to likely thermal energy from the collision. Using conservation of momentum, we can maybe somehow find the initial momentum of each vehicle and set it equal to the final momentums? However...
  19. R

    What is the y-component of the force by the floor on her during the collision?

    A previous question I got correct was: During this time interval, what is the y-component of the average net force on her? It was just 2625, and I thought question 2 would be the same answer but it wasn't. Not sure what to do.
  20. brotherbobby

    Two balls, dropped with a delay of ##\Delta t##, meet after rebound

    I draw a series of images of the problem situation. In (a), the first ball in green is (just) dropped at time ##t=0##. In (b), the second ball in red is dropped at time ##t=2\;\text{s}##. In (c), the first ball rebounds after a total time of falling down ##t_d##. At this position, its velocity...
  21. BikGer2

    Confused about a conservation of energy problem

    Hi, I assumed I was supposed to find the amount of kinetic energy body 2 receives after contact, assuming the collision is central, body 1 will be at rest after the collision. I started by using the equation for conservation of momentum: \begin{align} m_1v_1 = m_1v_1' + m_2v_2' \\ 50 * 20 =...
  22. D

    Why can't satellites be equipped with radar systems so that they can detect (and then avoid) impending collisions?

    Why can't satellites be equipped with radar systems so that they can detect (and then avoid) impending collisions?
  23. B

    Dead simple physics question (still a puzzle to me)

    an assumption being that since the M ( that is mass is a constant for the vehicle ) and a being the same as if the vehicle were to have been crashed into a stationary obstacle, that F would be the same as if said vehicle were to have been crashed into a stationary obstacle and not another...
  24. A

    What was the mistake in solving for the speeds of two marbles after a collision?

    Solved equation 1 for v1f and then substituted into equation 2 and solved for v2f. Got 2.22 as the answer, but it said the answer is incorrect.
  25. Rayan

    I Neutrino-Atom Elastic Scattering: Insights from Particle Physics

    What happens generally when a neutrino/anti-neutrino collides with a light vs heavy atom? My guess is, since neutrinos have very low cross section, their interaction is weak and therefore it will be an elastic scattering! For example: $$ \overline{\nu} + He^3 \rightarrow \overline{\nu} + He^3...
  26. S

    I Does being surrounded by water affect collisions between 2 bodies?

    Imagine there is a square plate fixed at the edge on all sides, it is impacted by a body with a pre-determined kinetic energy. Now assume that this plate is submerged in water and impacted by an identical body with the same amount of kinetic energy. Will the results be different? How to...
  27. Hak

    How Does Angular Momentum Conservation Affect Asteroid Collision Dynamics?

    Before the collision, the total linear momentum of the system is ##p = mv##, where ##m## is the mass of the minor asteroid and ##v## is its velocity. The total angular momentum of the system is ##L = mRv##, where ##R## is the radius of the major asteroid. Since there are no external forces or...
  28. A

    Work done during a collision -- Change in Kinetic Energy & change in Momentum

    Hello guys, I need help on this problem, "You throw a ball with a mass of 0.4kg against a brick wall. It hits the wall moving horizontally to the left at 30 m/s and rebounds horizontally to the right at 20m/s. (a) Find the Impulse of the net force on the ball during its collision with the wall...
  29. M

    Spring momentum conservation problem

    For this problem, The reason why I am not sure whether it is a valid assumption whether momentum is conserved because during the collision if we consider the two masses to be the system, then there will be a uniform gravitational field acting on both masses, and a spring force that is acting...
  30. P

    I Trajectory collision calculation

    Hello, I ask you for your aid in the solution of the following problem. Please see the attached illustration. Two objects (red and blue) are moving in the vicinity of each other. The red object is moving along a closed circle and the blue object is moving along a line. Our objective is to...
  31. D

    How do I stop my laser from destroying two items with one shot? (game design)

    Hi everyone I'm making a game in which a player's laser can destroy enemies and cancel out enemy lasers. My code for the player laser executes queue_free() when it enters the collisionshape for the enemy laser and enemy. The player laser is only supposed to destroy one item per shot...
  32. D

    Why doesn't my collision detection between two Area2D objects in Godot 4 work?

    Hi everyone I'd like to detect collisions between a circle and a floor. I have set them up as follows: The script runs fine (it's just a circle falling towards the floor), but nothing happens when the two objects collide. Does anyone know what I've done wrong?Thanks
  33. hagopbul

    I How to use physics to prove historical events?

    Hello all: Watching few news , titanic came and we start to have a question , can I prove that titanic was sunk because of hitting an ice mountain, and not because of torpedo, should we use material specifications , speed of the ship , and material specifications of the ice mountain or we...
  34. A

    Solving the Basic Mechanics Bullet Block Collision Problem

    $$ \frac{5E-3*v^2}{2} = (2 + 5E-3)(10)(0.2)(2) $$ v = 56.64 I just don't get how this is the wrong answer....it's just simple conservation of energy, right?
  35. KataruZ98

    Kinetic energy transfer from a rotating body in an inelastic collision

    The cylinder in question would have a moment of inertia of ~1.67kg*m² and rotational KE of 2.058J. At the point of impact also, assuming the body hits the sphere at a 90deg angle after traversing 90deg of displacement, it should(?) exert a force of 1.31N - enough to give an acceleration of...
  36. milkism

    Conservation of relativistic energy, collision of particles

    Question: With maximum do they mean that the speed of the pions is the same as the proton and an antiproton? Otherwise there will be two unknowns, and if I use both relativistic-energy and momentum conservation equations I get difficult equations.
  37. Zalokin

    B Understanding Physics for Coding Collision of 2 Balls

    Hi There! I am quite a beginner at physics and my aim is to apply physics to a computer program which I'm coding. The program consists of 2 balls of equal mass colliding into each other and demonstrating the trajectories after an elastic collision. I have already coded a more basic model...
  38. J

    2-D Momentum Problem -- Elastic collision of two spheres

    Hi, Here is the problem What is required to answer this question is two assumptions. Firstly, the component of the momentum normal to the centre line is the same before and after. Therefore, secondly, A must recoil entirely in the horizontal plane. This is the only way to answer this question...
  39. brotherbobby

    The gravitating of a small mass towards a big mass

    Diagram : I draw a picture of the problem situation and paste it to the right. Attempt : Let me assume that the position of the smaller mass ##m## at a given instant of time ##t## is ##x(t)##. (1) Gravitational potential energy ##\frac{GMm}{x} = \frac{1}{2}mv^2(x)##, where ##v(x)## is the...
  40. Darmstadtium

    B Conversion of Potential Energy: Sound or Heat?

    When a coin is dropped from a certain height and collides with a glass surface, is the majority of the potential energy converted to sound or heat? And how would one determine this as I only hear the sound and cannot measure the significant change in temperature?
  41. C

    I How to Calculate force exerted on a falling body?

    I'm curious about impact on falling object, so i have taken initiative to solve this problem. I considered only force on the falling object would be its weight and taken F=mg. With only limited data m=.25kg and drop height h=1m. Pondering on this consideration practically, it will have more...
  42. Like Tony Stark

    Collision between two particles with different spin

    1) The Hilbert space for each particle and the system are: ##H_1={\ket{\frac{1}{2} \frac{1}{2}}; \ket{\frac{1}{2} -\frac{1}{2}}}## ##H_2={\ket{1 1}; \ket{1 0}; \ket{1 -1}}## ##H=H_1 \otimes H_2## 2) I'm not sure what "considering the total Hamiltonian" means, but I think that the two CSCO...
  43. A

    Question about the solution to this elastic collision

    I found that 1/2m1v1i^2+1/2m2v2i^2=1/2m1v1f^2+1/2m2v2f^2 =>0.5*200*55^2+0.5*46*0^2=0.5*40^2*200+0.5*46*0*vf^2=>vf=78.713 m/s. The true answer is 65.2 m/s and is solved using m1v1i+mvv2i=m1v1f+m2v2f. Are these equations not interchangeable? Why can I not use the equation I used?
  44. A

    Question about two elastic collision formulas

    Equation 1 is equating the kinetic energies of the objects before and after the elastic collision. Equation 2 is equating the momentums of the objects after the elastic collision. They can be used interchangeably as long as the collision is elastic. Am I right in my conclusion?
  45. A

    Momentum in a perfectly inelastic collision

    I calculated:arctan(fy/13.0)=55=>fy=18.566 m/s Then I calculated, using the momentum equation: m1viy+m2v2iy=(m1+m2)vfy=> mv2i=2*m*18.566=>v2=37.132 m/s I thought that because the cars were stuck together, the kinetic energy from the northbound car would be lost. So, the speed would have...
  46. V

    B Collision time interval of a gas molecule with wall of container

    I have been trying to make sense of the derivation of pressure under Kinetic Theory of Gases chapter, but it's not making sense to me when the impulse momentum equation is used for the collision between a gas molecule and the wall of the container. The book says that for the elastic collision...
  47. M

    Where Did I Go Wrong? Solving for Angular Momentum in Air Table Puck Collision

    For part(a), The solution is, However, I made a mistake somewhere in my working below and I'm not sure what it is. Does anybody please know? Thank you! Here is a not too scale diagram at the moment of the collision, ## \vec L = \vec r \times \vec p ## ## \vec L = -y_{com}\hat j \times...
  48. M

    Puck collision with rod using angular momentum conservation

    For this problem, Why for part (a) the solution is, Is the bit circled in red zero because since the putty is released at a very small distance above the rod it velocity is negligible? Also for part (d) the solution is I did a computation of the initial and finial kinetic energies of the...
  49. M

    Induced polarization for collision between conducting spheres

    For this part (b) of this problem, The solution is, However, would a better explanation be: As the spheres are conductors, there will be free electrons within and on the surface of the conductors that will be polarized by the external electric field between the conductor. This will decrease...
  50. M

    Perfectly elastic collision between two electrons in ⊥ B-field

    For this problem, The solution is, However, is the reason why they don't include electrical potential energy because the time interval for which we are applying conservation of energy over is very small so the change in electric potential energy is negligible? Also, when they said, "electrons...
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