# 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 (...
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 ...
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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### 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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### 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 ...
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 ...
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 ...
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 ...
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....
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 ...
2k views

### 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 ...
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 ...
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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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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### 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. ...
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)...
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 ...
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 ...
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### 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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### 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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### 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 ...
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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### 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 ...
91 views