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Questions tagged [collision]

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

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If a object that's bigger than the other collides with one thats more massive, who wins?

So, let's say you've got two objects (A and B), A has a mass of 20 suns, while B has a mass of 10 suns, but A is only 10 suns in radius, while B is 30 suns in radius. If both objects collided, who ...
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How to calculate time of two objects collide? [duplicate]

There are two objects in the space. The first object has mass m1 of 10kg, and the second has mass m2 of 20kg. These objects (centers of mass) are 5 meters away (d = 5m). But how long does it take to ...
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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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4answers
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I recently solved a problem where a tenis ball is kept on a basketball and basket ball is at some height from the ground

. When the system is released the tennis bounces back to a larger height than it was before. what is the reason for this? I mean the problem assumes elastic collisions. How can the tennis ball rise ...
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Event Horizons and Events [duplicate]

How can two black holes with event horizons merge within the lifetime of the universe? Basically events are happening where events stop (to the outside observer) so does an event horizon actually ...
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31 views

Convergence of Milky Way and Andromeda

It is definitely a certainty that Andromeda will collide directly with the Milky Way in ~4 billion years. Has it been estimated how long the two galaxies have been attracted to each other to the ...
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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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Find impulse provided by the stopping object [on hold]

I have tried to understand this problem, but I'm still struggling with it. a 27g bullet hits a piece of wood and goes in 8.6 cm. if the bullet stopped in 0.44ms. what impulse did the wood provide?
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Why can't we expand the definition of the system until momentum is conserved?

So, here a ball initially moving with a velocity v and collides inelastically with a pivoted rod. I've learned that this is a classic example for the conservation of angular momentum. My question is ...
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Why does my bumper scrape when driving fast over a bump but not slow?

When driving my car over a bump or a quick change in gradient (from flat to uphill or downhill to flat), if I don't drive slowly and the bump/change in gradient is large enough, I'll end up with my ...
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Maximum distance covered by a ball with coefficient of restitution is e [closed]

A ball is dropped from height $H$, and the coefficient of restitution is $e$. Prove that the maximum distance covered by the ball is $(1+e^2/1-e^2)H$.
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Newtonian Mechanics- Method of Work [closed]

Q230: The question asks to find speed with which point mass M hits the wall when system is set free. I don't understand- It somehow doesn't fit in my intuition how mass M could hit the wall? Can ...
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481 views

Car and truck collision

When a car and a truck crash, the car seems to get damaged a lot more. Why does the car get more damaged then the truck in the collision?
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1answer
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How would you calculate the force of a hammer hitting an anvil? [duplicate]

If I were to hit an anvil with a hammer (let's say a 1 kg hammer at 1 m/s) how would the force of the impact be calculated? So, where I'm at with this is that I know the deal with f = mv, so the ...
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Kinetic energy transferred to a particle in a single collision: Cosmic Rays colliding with DM

I am reading a paper regarding energetic cosmic rays (CR) colliding with cold dark matter (DM) and thereby creating a component of DM with semi-relativstic momenta. (https://arxiv.org/abs/1810.10543) ...
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5answers
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Why isn't energy conserved in this collision problem? [closed]

I am stuck in a question where energy conservation is failing and momentum conservation is correct. I think I might be doing something wrong, that's why I'm asking this question. The problem is as ...
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If two identical objects (A and B) are dropped from the same height, and B has protective packaging, why is B less likely to be damaged?

I know this question has to do with impulse and collision, and if it were in numbers, I could give an answer to it, but how can I explain this in words? Both object A and B are identical, however, ...
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Completely inelastic collisions & center-of-mass acceleration

The system can be isolated, or non-isolated, and comprises of, say, two carts. If these two carts undergo a completely inelastic collision, will they then accelerate together at the center of mass ...
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2answers
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Why does height affect bounce efficiency?

I recently conducted an experiment, where I dropped tennis balls from various heights and recorded their rebound heights. The higher the drop, the higher the rebound height, obviously. However, the ...
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2answers
89 views

Are these collisions equivalent?

Similar to the question if two cars with a velocity of 50 mph each colliding is the same as one car colliding with wall at 100 mph, I was wondering if the same amount of energy is produced when ...
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2answers
69 views

How fast do nuclei need to be traveling when colliding for them to break apart? [closed]

I don't mean fission or fusion reactions with uranium or such. I mean gold or lead or even hydrogen collisions, such as in these particle colliders or outer space, wherein the nuclei seem to touch, ...
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36 views

Is the coefficient of restitution negative?

I recently came across a formula for the coefficient of restitution: Why is there a negative sign?
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1answer
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Mathematical proof that the centre of mass energy is the smallest energy in a collision

I recently answered this question about how the energy of a system of colliding particles is minimised in the centre of mass frame. I'm happy with the qualitative answer that treating the collection ...
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0answers
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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 is possible intuitive explanation of inelastic relativistic collsion?

In classical mechanics, we say an inelastic collision happens when some energy is transferred to heat and noise without changing the total sum of momentum. However, in special relativity, every ...
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Why is the laboratory frame energy always greater than the center of mass frame energy for collisions? [duplicate]

I looked through lots of sources to answer the question, 'Why is lab frame energy (total energy) always greater than the center of mass frame energy?' Many of them provided lots of mathematical ...
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3answers
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Why is the laboratory frame energy always greater than the center of mass frame energy?

I have been looking for an answer to 'Why is the laboratory frame energy always greater than the center of mass frame energy during collisions?'. A lot of resources provided mathematical explanations....
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2answers
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Can you anti-dot? (9-22 from Marion Thorton) [closed]

I'm solving a question out of the textbook and it reduces to the following. a particle of mass 2m with velocity $v_0$ collides with a particle of mass m at rest. The collision is elastic. So using ...
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4answers
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How is momentum conserved in this example? [duplicate]

Suppose a sticky substance is thrown at wall. The initial momentum of the wall and substance system is only due to velocity of the substance but the final momentum is 0. Why is momentum not conserved?
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1answer
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How did the Moon get into orbit?

It's the accepted theory that Moon was formed when an object collided with Earth, throwing off a lump of matter which became the Moon. But also, an object cannot be launched into orbit from a planet ...
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1answer
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COM frame in Relativistic particle physics

I have a home work: Consider a head-on collision of a 'bullet' of rest mass $M$ with a stationary 'target' of rest mass $m$. Prove that the post-collision γ-factor of the bullet cannot exceed:$$(m^...
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Question on hard spheres collision

My question is very simple: is it true that if I have a collision of two hard spheres, then the vectore of change of the momentum lies on the line connecting the two centers? Thank you!
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2answers
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How are particles in a collision chosen?

In synchrotron particle colliders, how are the particles which are collided chosen? For the most part, collisions of different types of particles don't do anything like you might expect in a video ...
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0answers
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How much water can an object raise after its fall? [duplicate]

Suppose that there is a small object (e.g. hand sized) with volume $V$ and mass $m$ that falls into a water container from a height $h_0$ and with initial velocity $v_0$. Is there a way to compute the ...
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2answers
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Collision between two non-deformable objects

Let say we have a non-deformable object and we release it into free fall and it hits the non-deformable floor. What would happen? Here is the way I think. Since the floor and the object are both ...
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Is it possible to model elastic collision of two rotating bodies (rotating rods hitting each other)?

If I understand it correctly the laws of conservation linear and angular momentum and kinematic energy isn't enough since these are just three equations and four unknown values. Another thing is there ...
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Is translational/rotational KE conserved when diatomic molecules collide?

When two diatomic molecules of a gas collide, is the collision elastic or inelastic? Is rotational KE also conserved/not conserved? My guess is that translational KE is conserved while rotational KE ...
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4answers
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Non-acceleration and 0 force

If a mass is moving at the rate of 30/ft. per minute for 5 minutes on a straight line and it strikes a second stationary mass and effects a change of position to this second mass, then we know from F=...
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3answers
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Force during collision between a body moving with a constant velocity and an accelerating body [closed]

Lets us assume that a train of huge mass is approaching me with a huge constant velocity of the order of hundreds of kilometres per hour. And little me is standing on the tracks but moving with ...
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1answer
55 views

Momentum and conservation of momentum [closed]

If an object that is moving collides with an object that is at rest and then they both move together what are the momentum and speed changes that take place
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1answer
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How can four-momentum be conserved in every frame in an elastic collision?

I have this problem: A particle B is standing still while another one, A, is moving towards it with initial 4-momentum $(E,p,0,0)$. Calculate the change in particle A's 4-momentum as viewed from ...
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1answer
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Smoluchowski theory of Brownian Motion

I am studing Brownian motion, in particular I am reading the book "Brownian Motion, Fluctuation, Dynamics and Application" by Mazo. Now I am dealing with Smoluchowski theory, but I am having some ...
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6answers
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Why does a billiard ball stop when it hits another billiard ball head on?

(I'm repeating myself a lot here, but it's because I want to make my confusion clear.) If 2 billiard balls are the same exact mass, and one hits another stationary one head on, I have heard that the ...
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1answer
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Calculate Linear Velocity and Angular Velocity After Collision, in SceneKit [closed]

Here is an attached scheme which i want to write my own custom wall reflection method to simulate the ball collision having right (or left, or top/back) spin. As an example, i have created wall node ...
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1answer
212 views

How is the rate of decay of a Newton's Cradle affected by the number of spheres in the system?

How does the number of spheres in a Newton's Cradle affect its rate of decay? (assuming only 1 sphere is released initially) From experiment, I observed that the rate of decay of a 5 sphere Newton's ...
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0answers
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What's the y-component in this relativistic collision?

In the book 'Physics' by Resnick, Halliday and Krane; they used a collision between two balls to explain the relativistic conservation of momentum. Here, two particles moving in the x-axis, after ...
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Why is conservation of momentum not valid here?

To explain my confusion, I would provide the following system: The two masses $m$ and $M$, with $M\gg m$, are moving towards each other(as directed by the arrows) with a common constant speed $V_0$. ...
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1answer
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Matter - antimatter collision [duplicate]

I have read that when matter and antimatter collide they just cancel out each other with the emmision of bright light. But doesn't it violate law of conservation of mass? If the the atoms dissapear ...
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3answers
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Why does a particle-antiparticle collision produce $2$ photons instead of $1$?

In one of the questions that I did, it asked: What is produced when an electron and positron collides with each other? The answer is $2$ photons. Why doesn't it merge into one? After all, the photon ...
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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.