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

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The Time That 2 Masses Will Collide Due To Newtonian Gravity

My friend and I have been wracking our heads with this one for the past 3 hours... We have 2 point masses, $m$ and $M$ in a perfect world separated by radius r. Starting from rest, they both begin to ...
7
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2answers
1k views

Physics of simple collisions

I'm building a physics simulator for a graphics course, and so far I have it implementing gravitational and Coulomb forces. I want to add collisions next, but I'm not exactly sure how to go about ...
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6answers
17k views

Is two cars colliding at 50mph the same as one car colliding into a wall at 100 mph?

I was watching a youtube video the other day where an economist said that he challenged his physics professor on this question back when he was in school. His professor said each scenario is the same, ...
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7answers
5k views

Would it help if you jump inside a free falling elevator?

Imagine you're trapped inside a free falling elevator. Would you decrease your impact impulse by jumping during the fall? When?
-1
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2answers
509 views

Two balls falling one above the other [closed]

Two balls, first with the mass $m_1$ and the second with the mass $m_2$ are falling from the heigh $h$. Suppose all the collisions are perfectly elastic and do not consider the size of the balls. $m_1 ...
8
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3answers
809 views

Number of planks required to stop the bullet [closed]

A bullet looses (1/n)th of its velocity passing through one plank. The number of such planks that are required to stop the bullet can be? Logically, to me the answer seems to be infinity, as always a ...
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2answers
6k views

Perfect elastic collision and velocity transfer

So my teacher told me that when you have two identical balls in a perfectly elastic collision, the first ball A will collide with B and afterwards A will stop and B continue. Why is this? Doesn't ...
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1answer
125 views

Where can I find the equations for “quasi” elastic collisions?

Yes, you all talk about neutrinos and spins, but I came out with this basic s**t :D All of us learnt the basic equations of collisions, elastic (everything bounces and energy remains the same), or ...
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6answers
9k views

Newton's cradle

Why, when one releases 2 balls in Newton's cradle, two balls on the opposite side bounce out at approximately the same speed as the 1st pair, rather than one ball at higher speed, or 3 balls at lower ...
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6answers
2k views

What would happen if Large Hadron Collider would collide electrons?

After some reading about the Large Hadron Collider and it's very impressive instruments to detect and investigate the collision results, there is a remaining question. What would happen if the ...
10
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4answers
765 views

Collision of Phobos

Mars has two moons: Phobos and Deimos. Both are irregular and are believed to have been captured from the nearby asteroid belt. Phobos always shows the same face to Mars because of tidal forces ...
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8answers
4k views

How can momentum but not energy be conserved in an inelastic collision?

In inelastic collisions, kinetic energy changes, so the velocities of the objects also change. So how is momentum conserved in inelastic collisions?
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2answers
131 views

What is the relative speed of two near-light speed particles headed towards each other?

I understand that nothing can move faster than light due to time dilation. I want to build upon my understanding of Einstein's theory of Special Relativity, so I came up with this hypothetical problem ...
2
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1answer
274 views

How to get the new direction of 2 disks colliding?

I'm developing a 2D game including collisions between many disks. I would like to know how I can get the angle corresponding to the new direction of each disk. For every disk I have this information ...
2
votes
2answers
301 views

Why can't collisions be elastic?

I understand that in inelastic collisions thermal energy is given out, but why does that happen? Why can't they simply rebound without giving off energy? Also, why in some collisions more heat is ...
2
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3answers
482 views

Train crash: are these situations alike? [duplicate]

I was just wondering... I believe that if a car travelling 50 miles per hour crashes into a wall, the result should be the same as crashing to another car also travelling 50 miles per hour (but in the ...
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1answer
736 views

Elastic Collision And Momentum

The question I am working on is, "Two blocks are free to slide along the friction-less wooden track shown below. The block of mass $m_1 = 4.98~kg$ is released from the position shown, at height $h = ...
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1answer
531 views

How are these balls reflected after they hit each other? [duplicate]

Possible Duplicate: Physics of simple collisions I have 2 photos of the balls, one before the collision and one after the collision. They do a elastic collision. I want to know how is the ...
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1answer
79 views

Ascertain the height an object has fallen from given force exerted and mass [closed]

An object of a given mass falls from an unknown height. If the force exerted by the object on contact with the ground is known, how would you ascertain the height from which the object fell?
64
votes
2answers
10k views

Why doesn't matter pass through other matter if atoms are 99.999% empty space?

The ghostly passage of one body through another is obviously out of the question if the continuum assumption were valid, but we know that at the micro, nano, pico levels (and beyond) this is not even ...
8
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3answers
328 views

Formalism to deal with discontinuous potentials in classical mechanics (hard wall, hard spheres)

It seems to me that Hamiltonian formalism does not suit well for problems involving instantaneous change of momentum, like particle collisions with hard wall or hard sphere gas model. At least I could ...
4
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2answers
1k views

Is there a 2D generalization of the coefficient of restitution?

The coefficient of restitution characterizes a collision in one dimension by relating the initial and final speeds of the particles involved, $$C_R = -\frac{v_{2f} - v_{1f}}{v_{2i} - v_{1i}}$$ In a ...
3
votes
2answers
1k views

What causes destruction in car crash?

Suppose a car crashes at a speed $v$ against a wall and comes to a stop. Now if the car crashes at $2v$, does that mean it suffers twice as much destruction, if that can be objectively measured? If ...
1
vote
1answer
100 views

Is the center of mass in general relativity equal to the center of mass in newtonian gravity?

Consider 2 point masses $A,B$ a distance $d$ away from eachother without velocity or rotation spin. Is the center of mass in general relativity equal to the center of mass in newtonian gravity ? In ...
10
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1answer
471 views

Mars just collided with Earth! A question of eccentricity

One of the standard theories behind the formation of our Moon is the giant impact hypothesis, according to which Earth was struck by a Mars-sized body (about $10\%$ the mass of Earth) early in its ...
7
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1answer
592 views

Anti-Matter for Neutrons

The anti-particle corresponding to a proton or an electron is a particle with an equal mass, but an opposite charge. So what is the anti-particle corresponding to a neutron (which does not possess a ...
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4answers
386 views

How to tell if the collision is elastic or inelastic?

I'm a programmer and a game developer, not a mathematician or a physicist. So please go easy on the math :) I know two things: How to find the new velocities of two objects after an elastic ...
5
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0answers
196 views

Hamiltonian function for classical hard-sphere elastic collision

I'm trying to find the Hamiltonian function for a system consisting of a single particle in one dimension colliding elastically with a wall at x = 0. Everything I've read on the topic (e.g. this ...
5
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1answer
507 views

What's worse, a full frontal impact or an impact at an offset?

Modern car designs have a crumple zone that absorbs most of the impact in a collision, and a strong "safety cell" in the passenger compartment that protects the passengers. These designs are put to ...
5
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1answer
301 views

How and why will the Milky way collide with the Andromeda?

Hubble's law says that the universe is expanding.How come the milky way and the andromeda are on a collision course?How will they end up colliding with each other?
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3answers
1k views

Newton's 3rd Law: How can I break things?

If I punch a wooden board hard enough and it breaks in two, has the board still exerted a force of equal magnitude on my fist? When the board breaks in two due to my force, the halves have a ...
3
votes
1answer
356 views

What is the function of the top point of a bouncing ball?

A ball is thrown away as parallel to x axis from M(0,h) point with speed V . After each jumping on x axis , it can reach half of previous height as shown in the figure.(Assume that no any air ...
2
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1answer
51 views

Collision of light waves & matter

When light or electromagnetic wave hits an obstacle, what happens? Are the reactions times always negligible? By reaction I mean all that happens after the hit like reflection for example.
2
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3answers
90 views

Elastic collision of point particle and rod

A 1 meter long rod on the ice with mass $m_2=1$ kg is perpendicularly hit on one end by a point particle with mass $m_1=0.1$ kg. The collision is elastic and the point particle is bounced back in ...
2
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0answers
58 views

Relativity addition and signs

I have just covered a very brief module on special relativity as a part of my physics course. I have also done some extra reading mostly; Morrin's Classical Mechanics. While I found the book really ...
2
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3answers
386 views

The theory of moon creation when a Mars size planet hit Earth

As we know the predominant theory where does the moon come from is that a Mars size planet hit the earth and took a chunk out of it which eventually materialized into moon. My question is that if a ...
1
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0answers
24 views

Elastic Collision [closed]

A cube has a side length of 20 cm. An atom in the gas moves around the cube as shown. It continually bounces off the four lateral walls of the cube. The atom has a mass of 6.6×10−27 kg. Because of the ...
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vote
3answers
346 views

Force when acceleration is zero

i tried to find it in books but i was unable to do so and i am not able to understand this and I couldn't think of a better example. i repeat. its just an example. if i punch someone's face with my ...
1
vote
3answers
151 views

Collision between a photon and a massive particle

Just a small question regarding collisions. Imagine a head-on collision between a photon and a particle with mass that moves with a non-relativistic speed, the particle was on its ground state, ...
0
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3answers
303 views

Conservation of momentum but not kinetic energy in inelastic collisions

In inelastic collisions, the kinetic energy of the system is not conserved but the momentum is. Kinetic energy is: $0.5 \times \text{mass} \times \text{velocity}^2$. Momentum is: ...
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1answer
55 views

How does this formula for calculating the “mass sum” in a collision translate to 3D?

According this tutorial, formula number 5: $$j = \frac{-(1 + e)((V^{A} - V^{B}) * t)}{\frac{1}{mass^{A}} + \frac{1}{mass^{B}}}$$ translates into formula number 6: $$j = \frac{-(1 + e)((V^{A} - ...
0
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1answer
385 views

Can a photon survive a collision? If so, is it at rest during the process?

Background Irving Kaplan, in Article 6.7: The Compton Effect of Nuclear Physics (2nd Ed.) explains the Compton effect as follows: Compton (1923) was able to show that when a beam of ...
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2answers
2k views

Two objects exert forces on each other, will the reactions affect them?

Two objects go in against each other, and then they collide, will object 1, exerting force 1, necessarily get on it a reaction equal in magnitude and opposite in direction? EDIT:- In my book it only ...