# Questions tagged [collision]

This tag is for questions relating to collision which is the interaction between two or more bodies that results in physical contact and an exchange of momentum between the bodies involved. When it happens, kinetic energy is often exchanged between the molecules’ translational motion and their internal degrees of freedom.

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### Can the parallel axis theorem be applied to find the moment of inertia about a new center of mass?

Consider a particle of mass m that collides and sticks to a rod of mass M hanging from a pivot at some distance d from the center of mass of the rod. The result of such a collision would alter the ...
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### Does the impact cause by object on other object depend on force applied by it or momentum of that object?

Does the amount of force an object experience at a high height in a waterfall is same as the amount of force the object experience at a lower height in waterfall? Does change in kinetic energy also ...
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### Full elastic collision in two dimensions with equal mass [closed]

I am currently dealing with a physics problem. It is stated that a pool billard ball collides with another. I guess it's a fully elastic one, it's not mentioned. Furthermore, it's stated that, after ...
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### Are photons and electrons "elastic" particles?

My teacher told me that Photons are elastic particles (allegedly it was a postulate of Max Plancks's Quantum theory too) and that during the photoelectric effect due to "elastic collision" ...
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The Device: Imagine a physical system involving two circular rings of distinct inner and outer radii, but equal in inertia. The smaller ring is superimposed inside the inner radius of the larger ring. ...
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### What are the implicit assumptions that make it okay to model a satellite fly-by of the Earth as a 1D elastic collision?

In a satellite fly-by of the Earth, a satellite approaches the Earth on a hyperbolic orbit. In learning about collision theory in Newtonian Mechanics, I have seen results related to elastic collisions ...
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### Question about ball collision in 2D and conservation of momentum & kinetic energy

I have a question regarding the collision of 2 balls (of the same unit mass m=1) in 2 dimension, please. We suppose that, right before the point of collision, the velocity of ball A was [1, 3]. The ...
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### Relative Velocity Addition Elastic Collision [closed]

From my stationary frame, a ball seen travelling at 0.7$c$ $+\hat{x}$ collides with a car travelling in the $-\hat{x}$ direction. After the collision, the ball travels at a speed of 0.4$c$ $-\hat{x}$ ...
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### Change in angular velocity of an initially non-rotating spherical object after a collision

In the theoretical scenario below: Will the object rotate? My first thoughts on this were: The initial angular velocity is $0$. This means it does not have any angular momentum (right...?) and it ...
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### Why is wingsuit water landing without opening a parachute not a survivable event?

According to this YT video, just before this wingsuit flyer opened his parachute his speed was below 90 KPH. When you jump off a 100 foot cliff your impact velocity is around 87 KPH and people have ...
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### Relation between Coefficient of Restitution and K.E

I know that Coefficient of Restitution(e) is defined as $$e = \frac{\mathbb{velocity\,of\,separation}}{\mathbb{velocity\,of\,approach}}$$ $$=\frac{v_2-v_1}{u_1-u_2}$$ Also for perfectly elastic ...
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### Conservation of kinetic energy in perfectly Elastic collision

Suppose two bodies of mass $m_1$ and $m_2$ moving with velocity $u_1$ and $u_2$ and they collide (perfectly elastic collision) and after collision their velocities are $v_1$ and $v_2$. Then by law of ...
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### Collision of 2 space ships using an Alcubierre drive [duplicate]

my question is which physics would i need to explain this problem ? an spaceship of mass 1 kg , is using a 'warp drive' to reach the speed $v=3c$ where c is the lightspeed then on the opposite ...
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### Height vs Pressure of a ball (using audio method)

I am doing an experiment for my IA which is me holding a basketball from one meter and letting it bounce at different pressures. For measuring this I am going to use a method that I have read about. ...
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### Calculate deceleration of a balls compression as it hits the floor, from air pressure and elasticity

A ball bounces for 2 reasons: A bouncy ball is made out of rubber, as that shape deforms and presses into the ground it restores itself to normal (because it elastic) and that converts the velocity ...
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### Conservation of momentum using impulse equations

There is an inclined plane on a frictionless surface. A ball strikes the inclined plane horizontally with velocity $v_o$ and moves vertically after collision with velocity $v$ (see figure) mass of ...
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### Gas particle collision rate dependence on particle velocity/ Hard sphere simulation

From a basic kinetic theory perspective the A-B collision rate $\theta_{AB}$ is given as a function of the mean speed and the number density.$$\theta_{AB} \propto \bar{C}_A n_B$$ If we are considering ...
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### Conservation of angular momentum in an inelastic collision

I have a question about the second method used to solve the problem above. The moment of inertia with respect to the stick's midpoint after the collision is $ml^2/12 + ml^2/4$ or $ml^2/3$ so the ...
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### General solution of a ball elastically colliding with a spinning rod

I am working on finding the general solution to a disc colliding with a thin spinning rod in two dimensions floating in free space. The collision is perfectly elastic. The width of the rod is ...
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### What's the best answer to "how many bounces until the ball stops"?

A problem question that has been coming has the form: How many complete trips between two plates moving towards each other can you make? (Given that you are moving between them at a constant velocity,...
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### Does precession affect loss of angular velocity in collisions?

I'm a higher schooler trying to do a project on how moment of inertia affects loss of angular velocity in spinning top collisions. Right now, I'm trying to find factors that might affect my results ...
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### How can the momentum be conserved in $y$ direction here?

In this question, A circus acrobat of mass $M$ leaps straight up with initial velocity $v_0$ from a trampoline. As he rises up, he takes a trained monkey of mass $m$ off a perch at a height $h$ above ...
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### When two balls collide with each other (not head on), will linear momentum still be conserved if there were friction between the balls?

As shown in this figure, where the surfaces of the two balls A and B are not smooth. Therefore, when they collide there will be frictions. My question is that since we derived the conservation of ...
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### Possible to destroy matter on a "human" scale (i.e. $\mathcal{O}(1m)$) using a proton?

A naive calculation suggests that a proton moving in a vacuum at $(1-10^{-38})c$ would have relativistic momentum equal to $\gamma mv \approxeq 2\mathrm{kgms^{-1}}$ if we say $m = 10^{-27}\mathrm{kg}$ ...
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### Can a X-ray photon increase its frequency after scattering of a nucleus?

Can a X-ray photon increase its frequency after scattering of a nucleus? Let say nucleons are oscilating inside a nucleus due to interaction between residual SNF and Coloumb force... Can this ...
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### How does collision of particles create more particles?

I mean, how do real particles get created in a collider like the LHC? Is it right that the LHC just gives energy to a pair of virtual particles that were generated by the quantum vacuum making them ...
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### Deformation of a ball when it falls on a rigid surface

Suppose, we drop a rubber ball on the floor. The ball collides with the floor, comes to rest and often bounces back up to lower height. I'm trying to look at this from the force perspective, not ...
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### What makes a ball bounce back up?

Suppose, I'm dropping a rubber ball on the floor and it bounces back up. I'm trying to understand this by considering the forces, and not using momentum, collision, or energy. Eventually, the ball ...
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### How to boost from CM system to lab frame with special conditions for the final state four momentum?

I simulate scattering events of a partonic 2 -> 2 process in the CM-system. Now I have added PDFs, therefore my four vectors of the initial state look the following:  p_1=(x_1\cdot\frac{\sqrt{s}}{...
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### Do golf balls fly faster than the swing speed of the club? Or are they equal? If not, how do golf balls fly faster than speed of club?

How is it possible that golf balls or for that matter baseballs or any such hit object can travel faster than the speed of the thing used to hit them?
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### How is partial elasticity calculated?

https://ophysics.com/e2.html The link above is a collision simulation and I can control the elasticity. I tried to make an equation to solve collisions given % of energy loss using the kinetic and ...
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### How do two water droplets collide in the space?

Suppose two balls coming towards each other with the same speed, collide head on, in the space (to neglect other external forces). After collision they will move along opposite directions. Then ...
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### How would colliding photons behave THROUGH a wormhole? not just colliding photons elsewhere [duplicate]

What will happen to photons when they are colliding to each other while travels through a wormhole ? keyword here is WHILE THROUGH WORMHOLE, not just simple collision of photons. Is it correct to ...
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### How to understand impulsive forces

Correct me if i'm wrong I was doing this thought experiment I have a few concepts that I'm confused Imagine a person of weight $50\rm kg$ and he's on top of a tower of height $20\rm m$ and he jumps ...
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### General formula for collisions involving rotation?

I am trying to write a 2d game engine involving collisions of convex polygons. Using the basic formula for elastic collisions I am able make my shapes collide realistically only considering their ...
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### Final speed of a two block system [closed]

Suppose a large block $M$ is moving in a smooth surface with speed $v_o$. Then a smaller block $m$ is carefully placed on it. Find the final speed I tried two methods which gave two different answers ...
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### Do we neglect Gravity to conserve momentum of colliding bodies?

Why do two bodies collide? What are the factors to be considered for collision? It is dependant on velocities of the colliding bodies if they do not have a sufficient velocity then they will perform a ...
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### Einstein needed to think carefully about collisions

I was reading Wikipedia article on Mass–energy equivalence. I accessed an old revision of the article, from 24 August 2020, https://en.wikipedia.org/w/index.php?title=Mass–energy_equivalence&oldid=...
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### Can gas in a room rotate a fan with asymmetrical spokes?

I was asked this question in an interview. The figure in first part of the question was drawn as shown. The question was to draw the angular position of the point marked on the rim with time. It ...
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### How fast do I need to go to run on water? [duplicate]

Well I was reading this article and I got stuck in this particular line because according to my calculations, the reaction of on my foot by the water should be $\rho A v^2 \sin^2\theta$. I am ...
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### Principle of conservation of momentum

when a nucleus at rest emits a beta particle, it is found that velocities of the recoiling nucleus and the beta particle are not along the same straight line. How can this be possible in view of ...
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### If I have $N$ particles which move in one dimensions, and that collide elastically, is there a way to solve for their trajectories?

There are $N$ particles on a line, and I know each of their masses and initial velocities and positions, and that the total energy and momentum is conserved when they collide. Is there a way to solve ...