# Tagged Questions

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

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### Star collision observation

What would these scenarios look like in real world? I mean, what the result would be?: 2 stars (not necessarily same mass) will collide "side by side", like in, they originally were traveling ...
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### Changing linear to angular velocity

Suppose a 1m rod with a hook is travelling at $v$ m/s, and the hook is caught on a hanging line. The rod will change its translational motion into rotation around the hook. Since it is not an ...
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### coulomb collision

I was reading an article by N. Bohr and came upon the following problem (the following wording is actually taken from a book by Thompson - Conduction of Electricity Through Gases): Let $M_1, M_2$ ...
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### Comparison of the effects of collisions from an NFL Nose Tackle and a Car with roughly the same momenta

If you get hit an NFL Defensive Tackle who runs at roughly 17mph (7.6m/s) it'd hurt a lot, but if you got hit by a normal car at 1.3mph (about 0.6m/s) it hardly hurts at all, and a collision from an ...
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### Particle hitting particles attached with springs [closed]

In classical mechanics if you have a particle moving in two dimensions and it hits a particle at rest although that particle is attached to a spring that is in turn attached to a third particle. ...
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### Ideal energy to study higgsstrahlung at a lepton collider

Referring to this diagram: I understand that any energy excess could be taken away as kinetic energy of the final $h$ and $Z$. If you are interested in this (kind of) process should you tune the ...
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### If one object, moving at a constant speed collides with another object - which is at rest - how much force has been applied?

This is one question for which an answer doesn't really make intuitive sense. In elementary school, we learn F=ma, but where's the "a" in a collision such as this? Edit: Plus, there has to be a force ...
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### What would put a harddisk drive (HDD) under 350G's of force?

I always see the label and it says 350G's withstandable. What would put this over 350G's? Is it even possible to hit 350Gs of force to a hard drive?
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### How to calculate impulse force on collision?

I've made a program which is supposed to simulate free fall of a ball on a ground. For collision with the ground I relied on calculating the impulse force with the answer in this Phys.SE question ...
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### Newton's law of restitution

Newton's law of restitution. Could someone tell me what the easiest form of this law to use is? I usually try to use e=(v(2)-v(1))/(u(1)-u(2)). Does the law also work if I don't know the direction of ...
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### Cube bouncing off a wall

An elastic cube sliding without friction along a horizontal floor hits a vertical wall with one of its faces parallel to the wall. The coefficient of friction between the wall and the cube is ...
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### Collsion in 2D, find angle and final momentum

Suppose that the collision is completely inelastic. Disregard friction as the surface is smooth. Suppose that one is in the direction of $(1,0)$ and the other $(0,1)$. Is the final momentum the ...
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### momentum equation to find velocity of solid particle after collision [closed]

If a particle collides with a liquid drop, particle might penetrate into drop and so the velocity of particle reduces. i.e. a sudden change in particle velocity happens right at the collision moment, ...
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### Can antimatter becomes black hole? [duplicate]

I know it seems unlikely to accumulate sufficient amount of antimatter to let it collapse under its own weight to become a black hole(maybe the gravity works differently I don't know) since they will ...
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### Can we create heavier particles with high energy?

It is known that an electron and a positron are created from the energy of gamma ray, is it possible to create heavier particles like proton and neutron from the energy of gamma ray? (if so what is ...
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### One extra conservation equation or angle relation for a relativistic collision

Edit: It seems that the derivation for the center of momentum frame was incorrect, due to the fact that the center of momentum velocity changes after the collision. This is also true for the ...
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### Collision and momentum conservation principle

Consider the following problem: A ball is dropped with an angle a between its direction and the normal of the floor and bounces up with an angle b between its direction and the normal of the floor. ...
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### Cosmology: collisionless vs collisional fluids?

I try to understand the difference between collisionless and collisional fluids in cosmology. My first question is the following. In the context of FLRW cosmology, we suppose that the Universe can ...
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### After a glancing collision, why do air hockey pucks spins around in circle?

For a lab testing the conservation of momentum, I had to hit an air hockey puck so that it would hit another stationary puck in a glancing collision. After the pucks collided, they travel their ...
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### Why does it hurt more to fall from 10 stories, than 1?

$F=ma$. Falling from any distance, mass stays the same, and acceleration due to gravity stays the same. So, why does it hurt more, the longer you fall?
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### Proton-Uranium collision

I am looking for references or numbers regarding what happens when one bombards Uranium with Protons. In particular: How to calculate how often does a collision occurs? Can a collision lead to a ...
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### Do inelastic or elastic collisions have any effect on a large bodies movement (like the Earth)

Recently read a question regarding the temperature of the CMB & one of the comments got me thinking... From what I understand, collisions between subatomic particles and objects out in ...
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### Inelastic Collision and Energy

How is is possible for momentum to be conserved and for KE to not be conserved? Momentum is related to velocity and velocity is related to KE, therefore if KE was lost, how can the system have the ...
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### Coefficient Of Restitution of Two Balls With Different Elasticities

In a computer program, I need to simulate the collision of two balls with different elasticity values given between 0.0-1.0. I looked for a formula to derive restitution coefficient from elasticity ...
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### Why two colliding bodies exert varying forces on each other during the course of their collison?

Suppose a bat hits a ball .What is the explanation of why the force is not constant during the course of the collison. At certain instants both ball and bat exert varying degrees of force on each ...
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### Why don't protons just bounce off each other in the LHC?

Ok, this might sound like a silly question, but I was wondering, when particles (e.g. protons) are smashed together in the LHC, why do they break up into dozens of other particles, as opposed to just ...
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### Newton's Third law of motion: A hammer hits a wall vs. hits a tire

When we hit the wall by a hammer, Newton’s third law says that hammer applies force on the wall (action) and wall applies force on hammer (reaction) equal in magnitude but opposite in direction ok ...
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### Newton's law for rigid bodies

Is newton's third law valid for rigid bodies? Say, if we have a bullet hit on a rod which is vertically placed on a rough floor. Friction is just sufficient sp that the rod rotates and does not ...
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### Average force for repeated elastic collisions

I was asked to compute the average force exerted by a rigid spherical ball (mass $m$) on the floor over time $t \rightarrow \infty$, in a situation where the ball is dropped vertically from a height ...
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### Two spaceships on collision course with cannonballs

Imagine two spaceships with a cylinder shape, travelling next to each other at the same speed. 4 cannonballs are exactly in their travelling path and they are about to get hit by them. One of the ...
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### Is my proof of the thought experiment that Walter Lewin proposed in lecture 16 valid?

A tennis ball bounces off a wall elastically. The momentum of the wall changes, but the kinetic energy of the wall remains zero. How is that possible? Walter Lewin Lecture 16 - Ball bouncing on ...
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### 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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### Does elementary particle emit photon?

Charged particles are accelerated by the magnetic field in a particle collider before allowed to smash together at specific location where the detectors are housed. My question is do the ...
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### In an elastic collision, can we choose between cons. of energy and cons. of momentum?

Suppose we have two solid spheres with masses $m$ and $M$, respectively, and that $m$ is significantly less than $M$. The lighter sphere is placed directly on top of the heavier one, and the two are ...
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### Simple question relating to physics prac reports

I am writing a physics practical report relating to the elasticity of materials relating to their momentum in a collision. I have values for the elasticities that are all within 2% of each other but I ...
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### Deriving equation for skipping stones over water

Why can rocks skip over water (stone skipping)? For instance, if you conduct an experiment where you drop both rocks from the same height, but give one considerable acceleration in the $x$-direction, ...
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### Using Conservation of momentum and Energy to solve a problem [closed]

A 9kg bullet is fired horizontally into a 10 kg block of wood suspended by a rope from the ceiling. The block swings in an arc, rising 6mm above its lowest position. Find the velocity of the bullet. ...
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### Collisions between an object and a wall

Is momentum conserved when an object bounces back against a wall? The wall doesn’t move, but the object moves in the opposite direction. Assume this is an ideal, elastic collision. If, initially, the ...
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### How can I learn about elastic bodies?

I'm writing a program that needs to be able to simulate a system of elastic bodies, that can collide with each other and with other rigid bodies, and deform accordingly. I think it would be an ...
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### Is this solveable? Simultaneous elastic collision of 4 objects in XY plane

I'm writing a computer program/game and can't figure something out; I want to be able to calculate the resulting velocities of 4 particles (hexagons, specifically) after they simultaneously ...
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### In an electron-positron annihilation, in what direction are the photons released?

I read that, in an electron-positron annihilation, at least 2 photons are produced, because of the law of conservation of momentum. my question is: in what direction are those photons released? and ...
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### Finding final velocity in inelastic collision [closed]

Information: In a shipping company distribution center, an open cart of mass 49.0-kg is rolling to the left at a speed of 5.40-m/s (see the figure). You can ...
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### What makes a collision superelastic?

I've seen an online definition: A collision in which potential energy is converted into kinetic energy so that the total kinetic energy of the colliding objects is greater after the collision than ...
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### The Coefficient of Restitution of a bouncing ball

If I drop a ball from a height $H$ and the ball rebounds from the floor it will bounce back up to a height of $e^2h$ where $e$ is the coefficient of restitution of the collision between the floor and ...
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### Why collide a moving particle with a particle at rest, rather than two moving particles?

I was just reading some lecture notes about relativistic and quantum mechanics, and in the later part of this page the author demonstrates that any relativistic particle collision in the "lab" ...
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### Can we generate electric current by injecting electrons into a copper panel

Suppose I take a vacuum tube and accelerate electrons in it by electric fields then collide it on a copper plate. Will the electrons then go inside it and generate an electric current by putting a ...
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### Two questions about the coefficient of restitution

If you were to drop a ball onto a surface from a height $h$ and the ball collided with the surface and then rebounded, would the ball then travel a distance of $eh$ back up from the surface where $e$ ...
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### Proving the conservation of 4-momentum for a particle collision $A+B\to C+D$

Let me say that particle A hits particle B and two particles come out - C and D; In system S I can write: $$p_A^μ+p_B^μ=p_C^μ+p_D^μ;\tag{1}$$ here $p_N^μ$ is the 4-momentum. Using the Lorentz ...