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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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Why don't objects bounce infinitely?

I'm computer programmer, and I was making a little test of my “possibilities”, so to speak, so I made a small game with sort of gravity, bouncing ball and walls around. Recently I've noticed that ...
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What kind of forces develop on a solid shape suspended in bubbly fluid? Is there a name for the study of this sort of interaction?

Let's say I have a solid shape - a sphere, a cylinder, I don't know if it matters - and I place that solid in a container of water. The forces on the shape consist of gravity and buoyancy (due to ...
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Overspeed Trip Valve Design

I want to estimate impact force generated due to collision between rotating body and stationary object. Bolt assembly is in balanced condition with the spring force and centrifugal force. As the speed ...
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29 views

Possible reactions due to antiproton-proton collisions

When an antiproton collides with a proton, then "all" reactions/channels are possible, right? Only constrained by the used energy and sure, some channels are more likely than others but in principle, ...
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Angular momentum conservation during collision

If I have a disk which is pure rolling and it strikes with a ladder, so can I conserve angular momentum about point O? I think I can because normal reaction passes through O, so torque due to it will ...
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What should be the speed of my bullet be to punch a nice round hole through a paper sheet?

If my bullet travels faster will the amount of damage done to the paper be lesser? Due to inertia of the paper can the bullet make bullet shaped holes instead of making a big hole as the speed ...
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Special Relativity; 3 Momentum Conservation

In SR, I understand you can use 4 momentum conservation, but what are the special cases where you can use 3 momentum/energy conservation? An example I have seen is with $$P_1=(M_1, 0) \\ P_2=(M_2,0) \...
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Do faster moving projectiles make larger penetration holes? [closed]

When it comes to shooting guns, a bullet of a certain size will make a certain size hole in the paper or wood target. A $.22$ bullet makes a pea size hole regardless of if its shot out of a pistol ...
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52 views

Change in momentum for gas particle collision with wall

I've attached the question as an image below as it's a graphical question. It simply states: "The diagram shows a gas particle about to collide elastically with a wall. Which diagram shows the ...
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1answer
70 views

What happens when in space a basketball flies and hits another resting basketball?

We have the following situation: In space, a basketball flies and hits another resting basketball. What happens next? a) Both balls fly in the original direction (but slightly slower) = momentum ...
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Net Force regarding Impulse and Momentum

I'm just going to preface this with: I don't know much, I've just started learning about impulse. Question: If there is a change in velocity regarding momentum $P$ then would there be a net force on ...
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Maximum scattering angle for relativistic elastic collision

In Landau Classical theory of fields, in the section of elastic collision(chapter 2, section 13), he mentions that for $m_1>m_2$, the scattering angle $\theta_i$ cannot exceed a maximum value, and ...
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Feynman's argument that at thermal equilibrium average kinetic energy of two gases are same

I had a hard time following Feynman's argument that when two different gases are present in the same box their average kinetic energy is the same at equilibrium. To quote from his book: ....Next, ...
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Collision angle relation to velocity of balls in Billiard Pool Game

I have a question about the billiard game physics. I know that in a billiard game, balls collisions are elastic and therefore the angle of the collision of two balls can easily be calculated no matter ...
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1answer
34 views

Dynamics of Event Horizons between head-on colliding non-rotating black holes [duplicate]

What happens to the event horizons of each black hole as the two identical non-rotating black holes collide head on? At a point exactly between them, is the curvature zero (do the individual ...
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What does turned through angle or deflected through an angle mean

The question says.. "The direction of motion of A is deflected through an angle θ by the collision." What does this mean geometrically? The whole question With theta being the angle being the ...
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Why are number changing interactions inelastic?

Inelastic processes are those in which the kinetic energy of the initial particles and final particles are not the same. Is this true also for number changing processes such as pair creation or pair ...
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45 views

If you get punched, is it better to be lighter or heavier?

I've seen people argue that lighter people can take a punch better because they can "go with it" better. This seems plausible to me, but is it really true? One reason why it seems plausible is that ...
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A basic formula of 1D elastic collision derivation

I found the folowing formula for 1d elastic colition: $$v_1 +u_1 =v_2+u_2 $$ (v,u means the velocity before and after the collision respectively) I tried to derivate it from momentum and energy ...
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If F(action) =F(reaction), why doesn't a ball bounce to its original height? [duplicate]

This might seem like a very absurd/ridiculous question, but this question suddenly popped on my head a few days ago. Is it that I'm missing something as I haven't reviewed this topic for quite a while?...
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Threshold frequency in photoelectric effect [duplicate]

If I take a metal sample and I throw light on it, and the emitted photons have frequency less than the threshold frequency required to make an electron come out of that particular metal. So the ...
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31 views

Why the lens is pushed to the right after light goes through?

I am asking myself why the lens must be pushed to the right in the following scenario: (image coming from Atoms and Sporks' nice video https://www.youtube.com/watch?v=UAmdoOX3870&t=327s) This can ...
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Conservation of Energy/Linear&Angular Momentum

If a ball hits a rod at rest at any position along the rod, the rod will be moving with the same linear velocity in each case. However, if the ball hits the rod away from its center of mass, the rod ...
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How does the collision between two atoms work?

Considering the quantum mechanical model for an atom, what exactly happens when two atoms (say, two Ca2+ ions in a Brownian motion) collide with each other? As I know, this collision is not like a ...
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2answers
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Momentum of solar panel after photon is absorbed [closed]

A solar panel installed on a car of mass 1 kg lying on a friction free road. Let the efficiency of the solar panel be 100%.let the momentum of photons be $m_o$ and and the car be at rest before ...
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In a collision, what causes solids to break?

example: A car crashes into a wall, breaking the wall into pieces at collision. Was it the transfer of of KE from the car to the wall particles that did this? Or the force exerted onto the wall by ...
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60 views

How is energy conserved in an elastic collision between two unequal masses?

In an elastic collision between two masses, if one mass is much heavier than the other, then the heavier mass will continue to move with same velocity while the lighter mass doubles its velocity. How ...
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4answers
96 views

Collision of block and a spring system kept at rest

A body of mass $m$ moving with velocity $v$ collides with a system of 2 blocks of each mass $m$ connected by a spring of spring constant $k$. All the three lie on the same plane (1D collision). There ...
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1answer
57 views

Classical Explanation for Electron-Ion collisions

Classically, electrons collide with other electrons and massive (by comparison), stationary positive ions as they conduct down a wire when an electric field is applied. Is there a good mechanism ...
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How is force exerted by an object in collision calculated?

If a car crashes into a wall, what data would you need to calculate the force the car exerted on the wall upon impact? Currently I’m thinking that you would need the cars mass and velocity(initial) ...
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Is there an example of two elementary particles colliding to result in a single elementary particle?

Apologies for the novice question, but I don't know enough particle physics to immediately answer my own questions. I have the following questions. Is there an example of an inelastic collision ...
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If Bernoulli's Principle may leads to a collision between two ships, then will it happen in a multi-ship situation?

I mean several battleships sailing on a sea towards the same direction. Some of them are parallel with short distances between each other. Could the pressure difference be cancelled out?
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Why doesn't Newton's third law mean a person bounces back to where they started when they hit the ground? [closed]

Why doesn't a person bounce back after falling down like a ball? If we push a person and he falls down then why doesn't he come back to its initial position. Although according to Newton's 3rd law of ...
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Kinetic Energy change in particle to wall collision

The Question A particle of mass m is moving in the +x direction with a speed v. It is approaching a massive wall which is also moving in the +x direction, but with a speed u < v (see figure) The ...
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Collision and simultaneity in special relativity

An almost rigid rectangle with length $D$ can rotate around its center. Assume that rectangle is horizontal and does not rotate before collision. According to observer $S$ two balls collide at the ...
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Why isn't acceleration always zero whenever velocity is zero, such as the moment a ball bounces off a wall? [duplicate]

The answer to this homework problem is $\left(\text{D}\right) :$ I understand why we rule out options $\left(\text{A}\right)$ and $\left(\text{B}\right)$ first. However, I don't get why $\left(\...
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State of $N$-body system after time $t$ (elastic collision & no gravity)

I am creating a gas particle simulator based game. All nodes (green circles) represent gaseous particles and collide elastically. My algorithm correctly accounts for two-particle collisions, as the ...
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How to determine particle energies in center of momentum frame?

I want to show for the following process that, except for the angle $\theta$, all momenta and energies are fixed by energy-momentum conservation. Namely: $$p_A=\frac{1}{2\sqrt{s}}(s+m^2_A-m^2_B\space,...
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Newton's law of restitution for extended rotating bodies

I just want to ask why does the law of restitution work for bodies which collide while rotating? For example, the rod with mass $m_2$ moves with velocity $v_1$ and hits the rod of the mass $m_1$. ...
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2answers
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Mechanics Question - Bullet fired into Block

I am studying for the GRE and came across this question (Question 93 from Sample Exam 2 in Kahn and Anderson's Conquering the GRE): A bullet of mass 5 g is fired at a block of wood of mass 1 kg, ...
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How much more damage is caused after hitting a brick wall at 100mph over 50mph? [duplicate]

How much more damage is caused after hitting a wall at 100mph over 50mph? It is clear that there is just twice as much force generated after hitting a wall at 100mph, since the deacceleration is twice ...
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2answers
61 views

Finding 3 unknowns in 2D-collision problem [closed]

While solving a 2D-collision problem, I obtained the following 3 equations: $$0.866\,|\vec v_{Af}|+|\vec v_{Bf}| \cos \theta_{Bf}=6$$ $$0.5\,|\vec v_{Af}|+|\vec v_{Bf}| \sin \theta_{Bf}=0$$ $$|\vec v_{...
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Invariant mass in special relativity [closed]

I'm following a special relativity course and I'm trying to understand how the invariant mass works. In particular I don't get how the following passages work. We have a collision between two ...
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542 views

Why does energy conservation give me the wrong answer in this inelastic collision problem?

Suppose there are two objects. The first object is stationary and has the next parameters: v1=0 m/s, m1= 4kg. The second object is heading towards the first one with speed v2= 8m/s and mass m2= 60 kg. ...
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Can a projectile bullet kill? [closed]

Today, I was watching a movie, in which a person shot a gun in air. The bullet went high in sky, became stationary for a moment and dived back and killing a non-innocent person by hitting him in head ...
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How can momentum but not energy be conserved in a collision, if objects keep moving in the same direction?

For example, there are 2 objects with the same mass, moving in the same direction, one with speed 5 m/s and the other 1 m/s. They collide and keep moving in the same direction, now one with speed 4 m/...
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Conserved quantities in ballistic pendulum

A bullet of mass $m$ hits a sandbag of mass $M$ that is suspended from the ceiling by a massless rope. At the moment the bullet hits it has a horizontal velocity $v$, and it gets stuck in the sandbag. ...
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How can a hammer of very less weight apply a large force when hit from a height?

Consider a hammer of weight 20N . When it is at on the table the only force it can apply on the table is it's weight. so it applies 20N when kept on the table . But when it is raised and dropped, the ...
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2answers
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Real life elastic collision and variation of kinetic energy

How small should $\Delta T$ be in a collision to be considered elastic? In elastic collisions $\Delta T =0$, but as far as I know, just atomic collisions are considered perfectly elastic. Then, which ...
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3answers
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How does conservation of momentum work here? [closed]

Imagine 2 oppositely charged particles attracted to each other, say an electron and a nucleus, assume their force of attraction is very large compared with any external applied force we're about to ...