# 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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### How can I begin this question? [closed]

A particle P collide inelastically with a singly ionized helium atom which is at rest initially helium atom He^+ is a ground state. After collision particle p found p particle scattered at an angle 90 ...
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### Angular momentum about multiple points of a system [closed]

A rod AB of mass ‘3 m’ and length ‘4 a’ is moving translatory with velocity u on a frictionless horizontal surface. A small particle of mass ‘m’ is moving with equal and opposite velocity of rod as ...
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### Condition for two points to collide with constant speed $v_1$ and $v_2$ at any point of time? [closed]

We have been given the initial speed of 2 particles. They have a constant speed. At any point of time $t\geq0$, their positions are given by $i+v\cdot t$ where $i$ is the initial position of the ...
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### How long will it take for a projectile to be knocked off a wall? (See details)

I am trying to calculate the impulse of an object that is thrown against a wall. Problem is, to calculate the impulse one needs to know not just the force, but also the time it takes for the momentum ...
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### 4-Momentum in Special Relativity [closed]

I have been given the following question; A ball of putty of mass $m$ travels at speed $v = 0.8$ towards another ball of putty of mass $2m$, which is at rest. After the collision the balls are stuck ...
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### Inelastic Collision of two balls [closed]

Is it possible that two balls of the same weight collide (in 1 dimension) and then stay at the rest? How is such a collision called? What are all the possible situations (velocities of 2 balls of the ...
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### Physics of an hypothetical animal attack (orca ramming through sea ice)

Question: Could an aquatic animal weighing 5,000 kg and traveling at 55 km/hr break through solid 11cm-thick ice? Context: I am writing a story and want the physics to be as accurate as possible. I'd ...
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### If a relativistic proton e.g. $\gamma=5$ hits a stationary proton will this collision take all its momentum?

In classical physics when a billiard ball hits a stationary one of same mass it transfers all its momentum to it so becoming itself stationary while the other gathers their whole momentum. But what ...
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### Predicting the oblique collision of two disks

Given two disks D1 and D2. Their radii, positions, and velocities are known. How can I predict whether they will collide or not? For a head-on collision, the angles that the directions of motion make ...
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### How do you determine energy transferred to a trampoline when a ball is dropped on it? [closed]

Suppose a ball of mass $m$ is dropped over a trampoline(consider the young's modulus of the material to be $Y$) from some height $h$. The ball impacts the trampoline, gets slowed down due to the ...
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### Where would the energy go if a nuke intercepted a meteor?

I thought of this question from watching the trailer for the new movie "Greenland" with Gerard Butler. Essentially in the trailer a huge comet falls towards the earth, apocalypse, etc. ...
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### Football Dynamics

Suppose a football is racing towards you at some speed $v$. What you are gonna do is try to stop it. There are two scenarios: 1.Suppose you hit it with your closed fist in the direction opposite to ...
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### Geometric calculation of the uncertainty in the collision of two hard spheres

I am trying to decipher how $d$ and $\delta \theta'$ $$d=\frac{L \delta \theta}{cos\alpha}$$ $$\delta \theta'=2\delta\alpha$$ have been calculated from the figure below I guess they must be using ...
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### Relativistic momentum in pion and muon

So this is from Griffiths particle physics book about pion decaying into neutrino and muon. The part I have problem with is that it states ` \begin{equation} p_{\pi}^2=m_{\pi}^2c^2 , p_{\mu}^2=m_{\...
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### 2D Elastic collisions and relative velocities

As mentioned in every text book I own, the relative velocities of approach and separation are equal and opposite for (only) 1D collisions. For 2D collisions, only the component of velocities along the ...
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### Validity of Elastic collision approximation

For elastic collisions, if the mass m1 is much much greater than m2, the velocity of m1 during the collision remains unchanged while the velocity of m2 can easily be found by Relative velocity of ...
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### What happens to the “last” of infinite beads (decreasing exponentially in mass) colliding on a straight line? [closed]

After reading a comment below I edited the question to simplify it. Imagine infinite beads on an infinite straight line, all at rest. The distance between all beads is finite. The mass of the first ...
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### Why is maximal kinetic energy lost in a perfectly inelastic collision?

A perfectly inelastic collision is one where both of the colliding objects stick together and move as one. My questions is, why, of all possible combinations of final velocities that conserve momentum,...
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### In matter-antimatter interactions, what's the meaning of “touch”?

In this question, the top answer gave a seemingly good description of the particle interaction, but what exactly the interaction is seemed to be left unstated. I've only the most rudimentary ...
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### How to determine the result of 2D elastic collision

As shown by the image, a disk of radius $R_1$ mass $M_1$ and initial velocity $V_0$ collides with another still disk of radius $R_2$ mass $M_2$. Both disks has no rotation initially. The direction ...
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### A “slick solution” to the kinetic energy lost when two pucks collide if they are pulled by the string that connects them [closed]

From David Morin's Classical Mechanics, problem 5.4 A massless string of length $2L$ connects two hockey pucks that lie on frictionless ice. A constant horizontal force F is applied to the midpoint ...
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### Ratio of collision of rate between distributions?

Background Consider the familiar setting of statistical mechanics, an assembly of $N=4$ distinguishable gas particles. Let, the total energy be $4E_0$. The possible ways energy of sharing energy ...
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### What is the relationship of inelastic mean free paths and EPES?

In the literature, they calculate inelastic mean free path of electrons by EPES (elastic peak electron spectroscopy) measurements? How these two are related? Why one can calculate inelastic ...
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### Why can a batter hit a pitched ball farther than one thrown by himself? [closed]

The main problem I am having is what Actually remains constant in the two cases. Is it the average force, or the time period for which the force is exerted? any helpful hints would be appreciated. ...
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### Collision of two balls/direct and indirect/elastic and rigid

I would like to know the complete equations for a collision of two perfectly elastic/rigid balls. I have seen something along these lines: $$m_1 v_1 + m_2 v_2 = m_1 v_1' + m_2 v_2'$$ but I think ...
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### Influence of geometry of collision on parameters after collision

In some of the physics problems I have done, the solution involves taking a snap shot right before collision and analysing the angles between the bodies. The angles between the bodies are supposedly ...
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### Behaviour of Bethe formula as particle energy grows

I have the following formula: $$\dfrac{dE}{dx} = \dfrac{4 \pi e^4 z^2}{mV^2}NB,$$ where, for example, in the case of relativistic velocity of a particle, we have B = Z\left[ \ln \dfrac{2mV^2}{I} - \...
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### How to find collision distance or impact time [closed]

I wanted to calculate the impact force of some falling object Let's assume this object has: $85kg$ mass the cross-section area: $0.75m^2$ (if that's necessary) Speed of $42.64m/s$ when it reaches the ...
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### Determining kinetic energy loss in inelastic collisions

I know there have been a lot of threads about this topic, but I haven't found one that answers my specific question. So if we have a case of two objects that stick together after colliding, with no ...
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### Inelastic Collision and Kinetic Energy

We see that our calculations always gives a loss of Kinetic energy in inelastic collisions while the net momentum of the system remains the same. Where does the lost energy go while there is no trace ...
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### Why electrical resistance decreases with cross sectional area?

With increase in cross sectional area the number of atoms with which electrons will collide will also increase in the same proportion. So basically the resistance shouldn't change with increasing wire ...
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### Rod hits rod - angular and linear momentum

I've been analyzing "ball hits a rod in space" type collisions, where speeding ball transfers part of its kinetic energy during elastic collision to the motionless rod, making it gain linear ...
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### Why can't we use the formula $v=u+at$ to get the value of $v$? [closed]

A ball of mass 0.2 kg falls from a height of $h=45 m$. On striking the ground, it rebounds in 0.1 sec with two thirds of the velocity with which it struck the ground. Calculate a ) change in the ...
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### Why cars rotate during small overlap crash test?

i was watching a small overlap car crash test video and i noticed that the car rotate to the right side during the collision. my question is why the car rotate? this is the link of the video https://...
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### The normal force acting between two bodies during elastic collision is conservative or or non conservative?

I read in the book that the normal force acting between two bodies during elastic collision is conservative , but I am not able to understand why this holds true because if the normal force is non ...
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