Questions tagged [collision]

Interaction between two or more bodies that results in physical contact and an exchange of momentum between the bodies involved.

180 questions with no upvoted or accepted answers
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What would the collision between a (large) solid planet and a gas giant be like?

Assuming a Jupiter-like planet and an Earth-like planet (Except, say... half the mass of Jupiter), what would happen when the two collide? For clarification: What would the actual collision be like? ...
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Baryonic density in collision experiments

Does anyone know any way of estimating the net baryon density in collision experiments, e.g. in LHC, RHIC, or the upcoming ones at GSI-FAIR? I have comes across many hand-waving arguments, sample - ...
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Angle between velocities: Elastic collision question in 3D

I have been given a scenario of a proton (particle 1) travelling with u1 = 3î+ 4j–6k and a Helium-3 nucleus (particle 2) travelling with u2= 3î+ 4j–2k. The two particles collide and the proton (...
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2answers
689 views

Calculating the Coefficient of Restitution Based on two Objects

The coefficient of restitution is calculated based on the velocities of objects before and after a collision: $$C_R = -\frac{v_{2f} - v_{1f}}{v_{2i} - v_{1i}}$$ The coefficient of restitution tells ...
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594 views

Plastic deformation energy dissipation due to inelastic collision

I have been attempting to determine an analytical expression for the coefficient of restitution (or any similar collision parameter) for an inelastic collision. So far, I've looked at Hertzian contact ...
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1answer
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Equivalency of conditions involving angular momentum of a rolling ball hitting a wall

(59th Polish Olympiad in Physics) A ball of mass $m$, radius $r$ and a moment of inertia $I = \frac 25 mr^2$ is rolling on the floor without sliding with the linear velocity $v_0$. It hit the wall ...
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1answer
49 views

Determining the velocity for a radial impact on an orbiting satellite

Say a planet P and a satellite S (the size of a moon) system exists and the orbit of S around P is circular. To make the satellite S crash into P, I can either slam an S sized comet C opposite to ...
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0answers
30 views

Deformation of an elastic ball

Suppose a free sponge ball is being compressed, due to applying a known force in a specific direction. The ball's shape will be distorted. Given are the direction of the applied force, as well as its ...
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1answer
40 views

Do all collisions (where the two bodies bounce away from each other) involve elastic deformation?

Does the stored potential energy in an elastic deformation provide the energy to push objects away from each other in all collisions when released, or only in certain cases like when striking golf ...
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2answers
84 views

How does the velocity of the fluid layers gradually increase towards the axis of a tube?

For a fluid moving through a cylindrical tube in a streamlined motion, a fluid layer in immediate contact with the wall of the tube remains effectively at rest. The layers away from the wall has ...
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How to estimate the kinetic energy loss of a rigid cube after it colliding with a heavy spring at rest?

In an environment without gravity, there is an unfixed, motionless, uniform spring with non-negligible mass m, length L, and stiffness k suspending and a rigid cube with mass M moving with velocity v ...
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450 views

What happens when an electron collides with an atomic nucleus?

Say an electron is shot towards an atom at such a speed that a violent collision (or just a regular collision) is unavoidable, what happens to electron and the nucleus? (Also, I'm a mere highschooler....
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2answers
516 views

How to estimate the impact force of a martial artist breaking bricks?

I was watching a martial artist breaking a stack of 9 out of 10 concrete bricks. I noticed that the last didn't break. It made me wonder if this would allow calculating the force dealt to be ...
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0answers
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How does Newton's cradle with balls of different mass behaves?

Conservation of energy and momentum governs Newton cradle. If $n$ balls were lifted, $n$ balls will bounce of on the other side. This happens if all balls have the same mass. Now, assume that you have ...
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1answer
59 views

How can you find the impact necessary to change the direction of Earth's spin?

If an object the mass of the moon was to hit earth's surface at an angle that would be in the opposite direction of earth's spin, how can you find how much momentum the object needs to cause earth to ...
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Can a projectile moving at supersonic velocities leave a silhouette in whatever it hits?

I was recently reading this, and Floris's answer confirmed my knowledge that the information of an collision travels at the speed of sound. While I was thinking about that, my mind wandered and I ...
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441 views

Trying to make a realistic simulation of 'breaks' (Pool)

I'm working on a 2D pool simulation project right now, and I'm trying to create good looking physics that are also performant. After collisions are detected, I update the velocities of the balls. So ...
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287 views

Relativity addition and signs

I have just covered a very brief module on special relativity as a part of my physics course. I have also done some extra reading mostly; Morrin's Classical Mechanics. While I found the book really ...
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367 views

Collision of Discs and Snooker Kicks

I woke up this morning thinking about spinning discs. Could someone verify whether my reasoning below is correct? Problem 1 Suppose have two identical uniform discs constrained to move in a plane. ...
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116 views

Lennard-Jones induced pseudo-molecules

It can be shown that the Lennard-Jones potential - which describes the interaction between particles in non-ideal gases - gives rise to pseudo-molecules: after a triple "collision" of three (classical)...
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141 views

How to formally write down the Boltzmann equation?

Can someone write down the Boltzmann equation, not neglecting any of the variables of the involved functions and integrals? Specifically, how to concisely capture the "primed" variables in a sensible ...
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How to write down the detailed balance (microreversed) amplitude

I know that time-reversal of a reaction and the detailed balance (microreversed, or reciprocal) reaction are different. Textbooks on scattering theory explain how to relate the S-matrix elements of a ...
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1answer
230 views

Two sonic booms colliding

If I theoretically created an experiment where I could create two sonic booms in directions such that the sonic "nose" is facing each other; what would happen? more specifically: Lets suppose I have ...
2
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1answer
386 views

Ball, Fixed Curved Track, and Non-Fixed Curved Track

I wonder whether the way I approach and solve this question is correct or not. Question: Case 1 As illustrated, a track of mass $M$ is fixed on a horizontal table. $AB$ is horizontal while $CD$ is ...
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2answers
107 views

What is the definition of a Collisional Fluid?

I am unsure whether this means the particles in the fluid must physically collide or does 'collisional' also apply to particles interacting in general, eg via gravity? I cannot find a good definition ...
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1answer
153 views

What is the physics behind a hard phone cover and a soft phone cover?

Does hard plastic distribute forces throughout a device, similar to how the shell of an egg works, much better than a soft cover does? This is the common argument I hear for the hard cover. How ...
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2answers
399 views

How to explain the momentum exchange of two solid particles collision at molecular scale?

Here is my question: assume two solid sphere collided to each other in vacuum, at macroscopic, it can be explain by Newton's law. But at molecular scale, does the surface atoms touch to each other or ...
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1answer
21 views

Newtonian-Mechanics .Elastic reflection

Question from the olympiad. Two planes move perpendicular to each other with speeds $v = 1m/s$. A body flies at them with a velocity of $u = 1 m/s$ at an angle $a=45$ to the surfaces of the planes ...
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91 views

Time taken by a cubic metal to stop after hitting a wall is independent of the velocity with which it hits the wall!

While doodling with stress and strain I came to a conclusion that the time,$t$,take by an object ( here a metallic cube) under elastic collision to stop when hitting a wall (with Young's modulus, $Y_{...
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1answer
65 views

Does universal proof exist for newton's experimental law for all cases of elastic collisions?

Newtons experimental law I. E velocity of approach is equal to velocity of separation (for the points on the two bodies where the collision takes place) for an elastic collision is applicable for ...
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26 views

Radiation from collision of two charged particles

Consider a collision between two electrons. Since each particle is accelerated during the collision, I assume each radiates energy according to the Larmor formula. Question 1: How much energy is ...
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Theoretically, Is it possible to create a nova by firing large masses into a sun?

In a science fiction story (Bobiverse) a nova is created by accelerating two small planets at relativistic speeds into a sun from opposite sides.The shockwave creates hydrogen fusion on opposite sides ...
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81 views

Can two black holes on a collision course, escape the merger?

Let's consider in this hypothesis that the two black holes have similar masses and approximation speed 0,99 c. At the maximum approximation point, only their event horizons are invaded slightly. The ...
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How does particle size affect the elasticity of a collision between two particles?

Lets say two particles in an aerosol collide. How does the size of the particles help determine if the collision is elastic or inelastic? I am specifically referring to the following quote. It ...
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67 views

Colliding elastically in lab and CM frame

Two spherical bodies of mass $m_1$ and $m_2$ are placed in gravity free space as shown. Initially, the body with mass $m_2$ is at rest and the body with mass $m_1$ approaches the other body with a ...
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What kind of forces develop on a solid shape suspended in bubbly fluid? Is there a name for the study of this sort of interaction?

Let's say I have a solid shape - a sphere, a cylinder, I don't know if it matters - and I place that solid in a container of water. The forces on the shape consist of gravity and buoyancy (due to ...
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1answer
45 views

Angular momentum conservation during collision

If I have a disk which is pure rolling and it strikes with a ladder, so can I conserve angular momentum about point O? I think I can because normal reaction passes through O, so torque due to it will ...
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1answer
48 views

If you get punched, is it better to be lighter or heavier?

I've seen people argue that lighter people can take a punch better because they can "go with it" better. This seems plausible to me, but is it really true? One reason why it seems plausible is that ...
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1answer
64 views

Classical Explanation for Electron-Ion collisions

Classically, electrons collide with other electrons and massive (by comparison), stationary positive ions as they conduct down a wire when an electric field is applied. Is there a good mechanism ...
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1answer
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Kinetic Energy change in particle to wall collision

The Question A particle of mass m is moving in the +x direction with a speed v. It is approaching a massive wall which is also moving in the +x direction, but with a speed u < v (see figure) The ...
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1answer
38 views

Calculating velocities of 2 squares after collision

If I have 2 squares each with random velocities, and both with the same mass, would it be possible to calculate their velocities after a collision, and how would I do so?
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Why are there no excitations by collision for the visible transitions in the Franck-Hertz experiment?

The minima of the I(V) graph for a Neon Franck-Hertz tube are approximately 20V apart from each other, this is usually explained by the fact that excitation by inelastic collision happens at about 20 ...
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Why do the colloidial particles in a viscuous fluid stop (stroboscopically) moving below a treshold as described in the experiment below?

In a nice experiment (inspired by the renowned physicist G.I. Taylor), which can be seen in this video (around 12 minutes), Professor David Pine and Professor Jerry Gollub filled a Couette cell with a ...
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Collision response with spring physics in RK4

I'm trying to figure out what's in the title. I've gotten regular spring physics working and now I'm trying to do something similar with actual collisions (player character colliding with the ground ...
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Why is there discrepancy in conservation of energy and momentum in my modified version of Veritasium's bullet board experiment?

https://youtu.be/BLYoyLcdGPc This is the Veritasium's bullet board experiment: A bullet is shot from beneath a horizontal board. The first time it is shot right underneath its centre of mass, and the ...
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Newtonian Mechanics - Regarding Conservation of Momentum in Collisions

In the question, it is given that all three balls are identical and are connected by a massless, ideal string (on a horizontal plane), and initially, the ball at the centre is given a velocity $v$. If ...
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2answers
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What are pre collisions and post collisions in forces and momentum?

What are pre collision and post collision exactly? I assume it is before collision and after collision. I can not find an answer on google.
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Is this a good approximation for the initial velocity of the electron?

I am studying the collision of a very fast proton ($E_p > 100$ MeV) on the electron of a metal (gold to be specific). Is it a good approximation to consider the initial velocity of the electron ...
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1answer
81 views

How impulse momentum theorem is put to use?

Guys the below link is a question already asked in this website and I have referred the answers given by the users and some of them were good ,but I have few doubts and I wanted to ask it in a comment ...
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Understanding the collisions of electrons and ion cores in the Drude model

In the free electron gas model, we assume that the conduction electrons are assumed to move freely throughout the conducting material which collide with the ion cores of the lattice. Image taken from ...