# 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.

1,854 questions
Filter by
Sorted by
Tagged with
52 views

### Kinetic Energy INCREASING in elastic collision? [closed]

Here is what I did, the initial conditions are, gravity exists , the hollow sphere has a downward velocity v0 right before colliding with the ground, an angular velocity v0/2R and ground is rough , ...
1 vote
55 views

### How are bubbles formed when a raindrop hits a flat pool of water?

I have noticed that raindrop impact can create a bubble on the surface of the water in a hot tub (104°F) up to several centimeters in diameter that is stable for several seconds before bursting. The ...
1 vote
22 views

### Energy conservation and Lorentz invariants [closed]

In relativistic collision theory,How can we deduce energy is conserved by using Lorentz transformation?
101 views

### What really determines punching force?

When it’s $F=ma$ why do some fighter like Francis Ngannou has the hardest punch although there are other fighters at same weight with more velocity. Does muscle strength has something to do with that? ...
33 views

### Minumum velocity for Newton's approximation for penetration depth

Suppose a rod-like object of length L collides with high velocity into some target. Newton's approximation for the penetration depth is ...
9 views

### What is the relationship between contact area in a collision and the volume of sound produced?

Greater contact area produces a greater sound in a collision, but why does that happen, and what is the proportionality?
65 views

### Two cars travelling towards each other with the same velocity and different mass. They crash. Which one has the largest acceleration?

Two cars are both moving towards each other with the same initial velocity of 50km/hr. One of the cars weighs 500kg, the other weighs 1000kg. They collide and stick together after the collision, ...
30 views

### Looking for a textbook that covers rotational collisions in depth

I am looking for a textbook that covers rotational collisions. I’m looking to understand “ball-off-wall” collisions. Topics might include reflection, the effects of spin on the ball, and treatment of ...
144 views

### What weight does a scale show when you throw an object onto it?

Imagine you have a bucket (cross-sectional area $A$) on top of a scale. Into the bucket you begin to pour sand (density $\rho$) with a mass flow rate of $\dot{m}$. The total weight of the sand in the ...
193 views

### What is the result of this Newton's cradle experiment where the initial ball doesn't bounce (exactly as in the regular case) but it has glue on it?

I have a question about a Newton's cradle type collision, but it has a twist to it. First, I will describe two well-known results, and then I'll add my twist. First, consider a cradle with five balls (...
20 views

### Why a spinning top bounces in a direction vertical to the surface that it hits?

When a spinning top slowly advances and hit a surface (a wall), intuitively one would expect that the top gets bounced mostly along the wall, due to the friction between the top and the wall. But the ...
130 views

### Energy gained by a black hole [duplicate]

Consider a massive particle falling into a black hole with a very high kinetic energy, for instance, an a particle with travelling at 99.9999999999% of the speed of light towards it. The mass-energy ...
40 views

### Conserving energy for a system

Let us assume two bodies which are moving with speeds $u_1$ and $u_2$. After an elastic collision,we assume the speeds became $v_1$ and $v_2$ respectively. Now let us treat the objects separately as ...
29 views

### What is the cross-section impact probability for an extended object moving trough a field of randomly moving particles?

In trying to get an estimate of the probability for an earth orbiting (LEO) satellite to collide with small debris particles. So I need to understand what is the impact probability for an orbiting ...
2k views

### Which way does a stone move when hit by a wheel/tire?

I don't think this exact question has been asked before in the physics section. I am mostly interested in understanding it conceptually rather than calculation. I have asked the same question in the ...
1 vote
55 views

### How to mathematically prove the balls move at equal speeds after an inelastic collision?

Consider a ball moving at a certain speed. It hits an identical ball at rest. After the collision, both the balls move at equal angles $\theta \ne 90^{0}$ (inelastic collision) with the original line ...
127 views

### 2d collisions of perfectly elastic circles with mass

My question is about 2 circles colliding. I can't describe it perfectly, which is part of the reason I'm stuck. Here is a picture. There are 2 circles. They both have an initial position, velocity, ...
70 views

### What is the combined mass of two relativistic particles inelastically colliding into a singular relativistic particle?

A perfectly inelastic central collision of two equal relativistic particles whose kinetic energies are equal to their resting energies results a single relativistic particle (and nothing but it). The ...
41 views

### How can you find the final velocity of a ball hitten by a train? [closed]

I want to clarify that I've already seen this question asked here , but I'm interested in how you'd solve it with the conservation of momentum rather with the relativity mechanism of finding the ...
12 views

### Requirements for a Simple Post-Collision Path Analysis

A wheel of mass $m_2$ is attached to the end of a rod of length L and mass $m_1$. The rod is pulled in the x-axis by a prismatic joint with a constant velocity V. The rod is attached to both the wheel ...
61 views

### Just a theoretical question about the geometry and form of the Black Hole

This is just something theoretical so please do not answer with a whole bunch of data but with a logical presumption about the next theoretical scenario.. There is a collision between a not so big BH (...
1 vote
16 views

### Why is only vertical component of velocity affected by 'e' during inclined collisions?

So far, all the homework problems I've solved involving a ball colliding (elastically or not) with an immovable wall at some angle $\theta$ with the normal assume that momentum is conserved ...
34 views

### Collision between rolling sphere and a cube

Consider a sphere (pure) rolling towards a non-moving block and colliding with its center elastically. (We are asked to find the velocity of the block after the collision) I thought to write down the ...
1 vote
91 views

### How does Newton's First Law uphold in this case?

Let say that there is no air drag. A ball is thrown towards me and I hit it with a bat. Here of course I apply some force in hitting it. Then can someone help me out by explaining how does the ball ...
33 views

### Elastic collision of two bodies, one in contact with ground [closed]

I came across the following problem. A hemisphere S and a particle P are of the same mass m. P is dropped from a height h. S is kept on a smooth horizontal surface. The particle P collides ...
40 views

### 2-body Umklapp scattering in graphene

It is claimed that the Umklapp scattering is forbidden in two-body collision in graphene due to the crystal symmetry in this paper . I am having a hard time to see why this is the case... why wouldn't ...
33 views

87 views

### Does Newton's Third Law still apply at impact with a surface? [duplicate]

Suppose that I were to jump on the surface of the Earth. The moment I hit the surface, shouldn't the force Earth is applying on me be greater than the force I am applying to it so that I stop ...
23 views

### Coefficient of restitution in Special Relativity (duplicate)

This is a duplicate of the question linked. I have not been able to find any treatment of this concept. Is it even possible to incorporate such collisions in SR, and if so, how?
144 views

### How do I define the initial jerk and yank of a cylinder subjected to impact of a rigid body at it's base?

I am trying to solve an axisymmetric longitudinal wave propagation problem during the impact (collision) of a rigid body and the base of a cylinder. On one end the cylinder is rigidly bound to the ...
15 views

### How fast can the ejecta from an asteroid impact go, while remaining solid?

A large asteroid strikes Earth hard enough so that chunks of rock from Earth are ejected back into space. Roughly how fast could these ejected chunks go, without receiving so much heat energy they ...
27 views

### Problem understanding the conceptual solution to a deformable system problem

A particle is suspended from a post on top of a cart by a light string of length L as shown in (a). The cart and particle are initially moving to the right at some constant speed, with the string ...
208 views

### Acoustic guitar pickups used in satellites: why? [closed]

Some years ago, a weather satellite manufacturer in the SFO bay area was buying small quantities of piezoelectric acoustic guitar pickups from one of the big music supply houses, which greatly puzzled ...
668 views

### In 1D, elastic particles do not converge to 1D Maxwell-Boltzmann

If we consider elastic particles in a 2D plane, their speed distribution will converge to a 2D Maxwell-Boltzmann distribution. For example, if the initial speed distribution is distributed uniformly, ...
76 views

### Why don't the net acceleration of the truck becomes zero after hitting the man? [closed]

Imagine, there is a truck of mass 'm' accelerating with an acceleration 'a', this means that the truck definately carries some force 'F'(let). Now, imagine the truck collides with a man standing ...
73 views

### How does one prove conservation of kinetic energy in collisions using time symmetry?

Consider two point masses colliding with each other, then, by conservation of momentum, $$m_1v_{11}+m_2v_{21}=m_1v_{12}+m_2v_{22}$$ But this doesn't characterize the complete movement of the two ...
804 views

### Photon collison with an atom

I'm currently studying atomic physics and have encountered a topic that I find challenging. My question is regarding the collision between a photon with an energy of, let's say, 12.20 eV and an atom. ...
3k views

### Why does a metal ball not trace back its original path if it hits a wall?

If we have a metal ball, why does it follow the law of reflection after it hits a wall? My point is that if it applies a force on the wall at an angle say 30deg below the horizontal (the wall is the ...
89 views

### How do you calculate the time taken in a collision?

For example a car with a known speed and mass crashes with a completely unyielding wall. The car has a crumple zone, (and you know the modulus of the crumple zone) so it doesn't stop immediately, but ...