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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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Gondolo-Gelmini change of variables integration bounds

In this article (Cosmic abundances of stable particles: Improved analysis, P. Gondolo and G. Gelmini, Nucl. Phys. B 360 (1991), p. 145-179,) Gelmini and Gondolo makes the change of variables from $(E_{...
QuantonPhysics's user avatar
1 vote
3 answers
77 views

Conservation of linear vs. angular momentum in two similar cases

I have a question that eludes my understanding: Imagine we have a bullet of mass $m$ and a rigid pendulum with a bob of mass $M$ hanging from a rigid rod of negligible mass hanging from the ceiling ...
Giovanni Piacentini's user avatar
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0 answers
30 views

The total horizontal distance traveled by a bouncing ball nudged off a table of height $H$ [closed]

Suppose a ball gently rolls off a flat surface of height $H$ and free falls to the ground subject only to the law of gravity. Once the ball hits the ground, it rebounds as shown in the figure. When ...
user42700's user avatar
  • 101
0 votes
0 answers
39 views

Idealized Newton's cradle

I was wondering about the conditions for an ideal newtons cradle. Under regular circumstances, the collisions are inelastic and a newton's cradle dissipates energy in various forms like heat, friction,...
Ritesh Nandi's user avatar
0 votes
0 answers
65 views

Justifying that the gold nucleus is at rest in a Rutherford experiment

This is an example on the Rutherford Experiment from Young and Freedman's University Physics. In the last paragraph of the solution the book states that it is valid to assume that the gold nucleus ...
nomadicmathematician's user avatar
-1 votes
2 answers
51 views

For an objective falling, reaching terminal velocity and then hitting the ground, how can I find the force it exerts on the ground? [closed]

For example object with v=tanh(0.1213)t/0.01236. m=69kg. I thought I had to use F=mv/t but that just gives the net force of the object while falling. I don't know how to find the force impacting on ...
Yifan YIN's user avatar
0 votes
5 answers
125 views

Direction of impulse

My textbook has the following problem: A batsman deflects a ball by an angle of 45° without changing the initial speed which is equal to 54 km/h. What is the impulse imparted to the ball? (Mass of ...
archthegreat's user avatar
0 votes
2 answers
42 views

Extra force in other frame paradox

Suppose there are two balls: one steel ball that cannot break with a mass of 10 kg, and another smaller wooden ball with a mass of 1 kg, which will break if a force of 10 N is applied to it. Consider ...
Paryag  's user avatar
0 votes
2 answers
63 views

Why do objects slow down when they hit the ground? [closed]

Say you drop an object on the ground. For the purpose of this question, I am just focusing on the slowing down of the object, not if it rebounds. I was just wondering which of the two reasons explains ...
user386598's user avatar
1 vote
1 answer
70 views

How do you solve instantaneous 3 body collisions

A few years ago I built myself a very basic python program that did some very basic collision mechanics between particles with a mass and velocity and it was helpful in learning a few things and ...
Max's user avatar
  • 111
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0 answers
59 views

What are the characteristics of a non-relativistic collision?

I have a physics test tomorrow on special relativity and one of the questions on the previous test was as follows: "A particle of mass m hits another particle of the same mass that was originally ...
fiene's user avatar
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2 votes
3 answers
81 views

Do bodies stick together after an inelastic oblique collision?

My question is particularly about an oblique collision case. (For example a body having velocity along x axis approaching another with velocity along y axis) From what I know, in perfectly inelastic ...
User's user avatar
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0 votes
1 answer
30 views

Will the expression be same for $n$th and $(n+1)$th Coefficient of restitution?

Let's say a ball is dropped from the height h on the ground and bounces repeatedly. If the coefficient of restitution is e, the height to which the ball goes up after it rebounds for the $nth$ time is ...
Moksh Singh Dangi's user avatar
0 votes
1 answer
75 views

When two objects collide, which directions do they go in after the collision?

I am watching this video here: https://www.youtube.com/watch?v=KPhMMnIocR0&list=PL4VRaRxeNj-1F-JukcRVAzbiIi0ibrHqy. At 11:02, the author shows a simulation and says that for a Galton Board (https:...
bula's user avatar
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4 votes
2 answers
757 views

After how many bounces will a ball's mechanical energy equal zero?

This was a question I asked myself for fun. It turned out to be more difficult than I initially imagined. The Problem: Let's say a ball is dropped from h0. Air friction is negligible. The collisions ...
jazzblaster's user avatar
3 votes
2 answers
85 views

Why do basketballs with more air in them bounce more than ones with less air?

I thought it this because more air means more pressure, so there will be more pressure when the ball is deformed and it will gain more kinetic energy as it rebounds. However, some sources say that ...
user386598's user avatar
0 votes
0 answers
40 views

Time of collision of two particles arriving with Planck time difference

Suppose two particles, $A$ and $B$, arrive at a certain point $P$. After arriving, whichever particle arrives first stops until the other particle arrives later and collides with it. Now, let's say ...
Andremoniy's user avatar
1 vote
1 answer
43 views

Loss in KE in terms of reduced mass and coefficient of restitution

(This is very similar to this question - except I have derived the equation and am now looking for a simpler way.) The Equation The change in the systems overall KE after a collision between two ...
Anis Manuchehri-Ramirez's user avatar
0 votes
1 answer
48 views

Elastic scattering and conservation of spin

I am trying to understand conservation of spin in QED elastic scattering in these nice notes (VJ Martin, Particle Physics, Spring 2012, University of Edinburgh): https://www2.ph.ed.ac.uk/~vjm/Lectures/...
Mister Mak's user avatar
0 votes
1 answer
49 views

Mandelstams for $2\to 2\to 3$ process

2 initial particles become two other particles, from which one decays into 2. Let $p1$ and $p2$ be the momenta of the initial particles, $p3$ the momentum of the decaying particle, $p5$ and p6 the ...
Ville Alanko's user avatar
2 votes
0 answers
56 views

Derivation of the Coulomb Collision Operator for Plasmas

I am attempting to learn about Coulomb collisions in the kinetic theory of plasmas. In doing so, I have come up with an "intuitive" derivation of a Coulomb collision operator. However, the ...
MeowBlingBling's user avatar
0 votes
1 answer
56 views

What if dark matter and anti-matter collided? [closed]

Considering we know both dark matter and antimatter can interact via gravity, just like regular matter, then that means the two can gravitationally interact. However, since dark matter does not ...
Quantum Wonder's user avatar
3 votes
1 answer
68 views

Finding the cross section for the proton-proton fusion reaction

I have been looking at the cross section $(\sigma)$ for the proton-proton collision in plasma. From what I have researched, the cross section cannot be found experimentally so it must be found through ...
Waev's user avatar
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0 votes
0 answers
43 views

Mean free path equation for plasma

Does the mean free path equation $$\lambda=\frac{1}{\sqrt{2}\pi d^2 n_v}$$ work for collisions in plasma or just for gas?
Waev's user avatar
  • 33
6 votes
3 answers
1k views

Conservation of momentum in Newton's cradle

Imagine a Newton's cradle with 5 balls with mass of each ball is $m$. In a case where two balls are dropped against three balls, if we write an equation considering that momentum is conserved, $$ 2mu=...
Yara Try's user avatar
  • 145
0 votes
3 answers
207 views

Rotational mechanics in collision of a mass and a rod

Suppose a small particle of mass $m$ moving at a velocity $v$ collides with a rod at the end in a perpendicular direction to the rod. I am sure that the rod translated in the direction same as the ...
Athulkrishna.S's user avatar
0 votes
0 answers
33 views

Energy distribution in atomic collision

A photon of energy 10.2 electron Volt collides with a hydrogen atom in ground state. After a certain time interval of few microseconds another photon of energy 15 electron Volt collides inelastically ...
Nandini's user avatar
0 votes
1 answer
47 views

Rutherford scattering closest approach distance

Consider a particle 1 moving towards a particle 2 at rest. In class, my teacher said that in order to derive the minimum approach distance when the impact parameter ( b ) is 0, we had to use ...
Lucas's user avatar
  • 319
0 votes
1 answer
62 views

Would it be possible to build a device or structure that could absorb the impact of an asteroid?

This is probably a stupid question but as the title says would this be possible. I'm imagining some kind of large structure which absorbs the impact rather than deflects it and then, a step further ...
ollie ao's user avatar
2 votes
2 answers
542 views

According to Newton's Third Law why is there a difference in movements between collisions of different mass (please read description)?

When an object of some mass hits and rolls towards another stationary object of the same mass, the ball that was rolling stops. However, if we use the same ball from that scenario, and roll it at the ...
John's user avatar
  • 23
0 votes
2 answers
69 views

Ball colliding with inclined stationary plane

A particle with mass m1 is dropped from a height onto an incline plane creating the angle $\alpha$ with the ground (the slope is frictionless). The coefficient of restitution is e. Find the angle $\...
Alexander Jonsson's user avatar
0 votes
2 answers
56 views

Would placing sand bags over the top of a car's strut housing reduce the jarring impact felt when the car hits a pothole? [closed]

I live in an urban area where many of the streets have pot holes and some of these streets have some very large and deep potholes. I have been wondering lately if it would be worth the effort to try ...
WaterSparkle351's user avatar
0 votes
1 answer
44 views

How does the coefficient of restitution affect the velocity after?

I know that for a vertical or a horizontal impact the coefficient of resititution (e) affects the velocity in that direction $e=\frac{v'_{2x}-v'_{1x}}{v_{1x}-v_{2x}}$, or y if it is vertical. But what ...
SSL2's user avatar
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0 votes
0 answers
26 views

Generated pressure when two water interfaces collide

Background I'm studying a bulk cavitaion problem as described in V. J. Cushing - On the theory of bulk cavitation. In the problem an incident shock wave (from the water $z < 0$) is reflected as a ...
MOOSE's user avatar
  • 13
-1 votes
1 answer
36 views

Momentum conservation and collisions [duplicate]

Whenever a collision happens on a rough horizontal surface, because the frictional force will be external to the system, momentum wont be conserved. However, can we consider the friction to be ...
Krrish Gupta's user avatar
0 votes
0 answers
41 views

Why does a ball bounce off the wall? [duplicate]

When we throw a ball onto a wall, the ball comes in contact with the wall. And the velocity of the ball comes from V m/s to 0m/s. According Newton’s first law, a force was acted on the ball by the ...
Akhilesh G's user avatar
0 votes
1 answer
26 views

What happens if an object hits stationary objects on a pulley?

What happens if an object with speed $v_i$ and mass $m$ hits two bodies of equal mass (also $m$) on a frictionless pulley at rest, and the colliding body sticks to one of the bodies on the pulley? I ...
John greg's user avatar
  • 103
0 votes
1 answer
89 views

Is it possible to have a uniform speed but variable velocity in one-dimension motion?

Is it possible to have a uniform speed but variable velocity in one-dimension motion? I saw a lecture where teacher said that it is possible if particle changes its direction of motion 180$^\circ$. ...
NOTE Book's user avatar
0 votes
1 answer
43 views

Conservation of Momentum in particle splitting. Is it always conserved?

Let an intially stationary particle $A$ of mass $m$, if $A$ explodes such that it breaks into 2 equal pieces.(Assume no heat or sound energy loss) The red point is supposed be the point at which the ...
SHINU_MADE's user avatar
0 votes
2 answers
43 views

Are Coefficients of Kinetic Friction Additive?

Question setup: Say we have two blocks on a $30^{\circ}$ incline plane with masses $4\ kg (A)$ and $8\ kg (B)$. The coefficient of kinetic friction between block $A$ and the plane is $0.25$, and that ...
trb7074's user avatar
1 vote
2 answers
61 views

A block experiencing a constant force collides with a stationary block

If a constant force is exerted on a block 'A' on a frictionless surface and if it collides with a stationary block of a lesser mass on the same surface (let's call it block 'B') then upon the ...
Rohan Rajasekar's user avatar
0 votes
1 answer
84 views

Restitution and inelastic collisions

If particle $A$ and particle $B$ collides in plane or space, we can calculate the impulse $\vec{J}$ from $B$ to $A$ with $$ \vec{J}=\frac{((\vec{v}_A-\vec{v}_B)\cdot\hat{n})(\epsilon+1)} {\frac{1}{m_a}...
magistern's user avatar
0 votes
4 answers
51 views

Force of impact on a body [closed]

This is a pretty silly question which got me pondering for a while. We know that Force of impact on a body is given by $\frac{m(v_f-v_i)}{t}=\frac{mv_i(e+1)}{t}$ where e is the coefficient of ...
Star Gazer's user avatar
0 votes
0 answers
23 views

Circle to Polygon & Circle to Circle Velocity Resolution

I current am working a 2d physics engine, but have recently hit some bumps in the road. Polygon to polygon collision and velocity resolution works without issue, but I am struggling to get working ...
TrippR's user avatar
  • 1
0 votes
0 answers
56 views

What level of energy could an amateur particle accelerator achieve?

I am a member of a group of high schoolers and we've been looking to set our sights on a challenging project to dump some time into. Currently we're investigating how realistic it is to attempt ...
bakedsteak's user avatar
2 votes
4 answers
98 views

Forces equal and opposite in elastic collision with different masses?

I just learned about conservation of momentum in my mechanics class. So say we have two objects, one moving towards another at rest. I know that in an elastic collision with identical masses, the one ...
Arjun Chopra 's user avatar
3 votes
3 answers
702 views

In this conservation of momentum problem, where is the sign error coming from?

Say I have a particle travelling in the $x$-direction and breaking into two pieces: Conservation of momentum in the $x$-direction obviously gives: $$mv = m_1 v_1 \cos(30) + m_2 v_2 \cos(60).\tag{1}$$ ...
Allure's user avatar
  • 21.4k
2 votes
0 answers
62 views

Why is it so much easier to kick a basketball when it is just bouncing back from the ground?

A basketball coach showed me that when you bounce a basketball back from the ground, it is much easier to kick it far away (actually it shoots out like a rocket), but when you want to kick it like a ...
Árpád Szendrei's user avatar
0 votes
3 answers
73 views

Is the net force on centre of mass always equal to the external force applied on one block of a two block system connected by a spring?

I came across a question which says- "Two blocks of equal mass m are connected by an unstretched spring and the system is kept at rest on a frictionless horizontal surface. A constant force F is ...
Synthia's user avatar
  • 57
0 votes
0 answers
52 views

Standard deviation for a free path distribution

I would like to be able to describe a particles path before collisions with greater precision. We can calculate the "mean" free path of a particle before colliding moving particles, but I ...
Roman Grachev's user avatar

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