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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Can someone explain what is the force the ball will exert?

If a ball is falling under free fall then the force exerted by the ball on the ground would be $mg$. But that's not the case in real life ball would hit with more force. But when i draw free body ...
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Do individual rest masses change in a relativistic elastic collision?

Consider a classical isolated relativistic elastic collision of two free scalar point masses in 1 D. The aim is to get the final velocities of the particles given initial rest masses and initial ...
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Radiation from collision of two charged particles

Consider a collision between two electrons. Since each particle is accelerated during the collision, I assume each radiates energy according to the Larmor formula. Question 1: How much energy is ...
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From the frame of reference of a colliding object, does the entire universe change direction when it bounces?

Consider three objects: a rubber ball, a spaceship, and an isolated brick wall floating serenely in the vacuum of space. From the perspective of an observer on the spaceship, the ball is moving ...
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A ball of mass $m$ is dropped from a height $h$ on to a rigid floor. If $e$ is the coefficient of restitution [on hold]

A ball of mass 'm' is dropped from a height 'h' on to a rigid floor. If e is the coefficient of restitution, the time required for the complete bounce is? After finding the initial and final velocity ...
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Theoretically, Is it possible to create a nova by firing large masses into a sun?

In a science fiction story (Bobiverse) a nova is created by accelerating two small planets at relativistic speeds into a sun from opposite sides.The shockwave creates hydrogen fusion on opposite sides ...
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Will a man falling from a great height and a man lying on ground exert same amount of force on the earth?

Suppose in a situation there is a man falling from a height, when he falls from a height and touches the ground then he applies some force on the ground which is equal to his weight, and in another ...
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Is the coefficient of restitution always equal to the square root of the ratio of final kinetic energy to the initial kinetic energy?

The coefficient of restitution (COR) according to some sources (https://en.wikipedia.org/wiki/Coefficient_of_restitution) is equal to the square root of the ratio of final kinetic energy to the ...
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Why is the momentum always conserved in elastic collision?

As the title above, why is the momentum always conserved in elastic collision (no loss of kinetic energy)? Does it related to the conservation of kinetic energy? If so, how do we prove that? Further ...
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How do we calculate the force applied by a ball on a wall which bounces back? [on hold]

If we have a ball which we throw toward a wall which touches the wall and bounces back then how will you calculate the force applied by the wall on the ball because the the contact time of the ball ...
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Newton's Third Law of Motion? [duplicate]

Newton's third law of motion states that every action has an equal and opposite reaction. But, on punching a wall, I feel much greater force than on punching an inflated balloon. So, what does it mean?...
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Kinematics: One dimensional motion

If a particle is moving in one dimension with constant speed, can we say acceleration is zero at all the points? Answer given in my textbook is yes acceleration is zero. But I think it can undergo a ...
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What would Happen if a Primordial Black Hole, with 5-10x time the mass of Earth, were to fall into our Sun?

So lately i heard of this theory that planet 9 might be a Primordial Black Hole (PBH) with 5 - 10 times the mass of Earth. I was thinking to myself, what would happen, if such a PBH (if it even exists)...
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Why does body with continuous speed generate force?

So... sorry if the question seems a bit stupid, but it's been nagging me all day and I couldn't find an answer on the net. It goes like this: If a body, say, a car is moving with constant speed. This ...
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Collisions in a System of Bodies

There are three blocks A,B and C, with B and C at rest connected by a light spring and A moving with a velocity v, all three lying on the same horizontal frictionless surface. After some time A ...
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1answer
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Why is tangential particle momentum conserved in a collision?

In my dynamics class, we learned that the individual momenta of two colliding particles is conserved in the direction tangential to the collision. Why would this be the case? Consider the diagram ...
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Work of a fixed wall

In this link here, What work is done by the wall when a ball hits it? The answer to the question if a wall performs work when hit by a ball was, that the wall does no work if it isn't displaced. But ...
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Reaction Force or Normal Force? [duplicate]

When we punch a wall our hand hurts... Do we feel the pain due to the normal force exerted by the wall or due to the reaction force?
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Where is the momentum going?

When a ball of mass $m$ collides elastically having velocity $v$ with a wall, then it retraces itself with the same velocity. Impulse on the ball due to wall is $2mv$ and since there is no external ...
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Energy loss in sticky collisions

A typical problem of sticky collisions involves an object colliding with an object at rest on frictionless surface, and the two move together. If conservation of momentum is applied we get $ v'=\frac{...
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Are black holes bound to merge once their event horizons touch? [duplicate]

Even if they move toward each other at relativistic velocities and not head-on? I looked at questions Black hole collision and the event horizon and Dynamics of Event Horizons between head-on ...
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1answer
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Newton's cradle faster than light? [closed]

If we have a Newton's cradle toy where the balls actually touch each other. Can energy be transferred from the first ball to the last one faster than the speed of light? And what factors control the ...
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Why doesn't an accelerating body on collision come to rest immediately? [closed]

Let us consider two bodies (A and B) lying on a surface at a certain distance from each other. Let A be accelerating to the right, towards B and hence, the force experienced by A be F. When A collides ...
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Collision of Rolling body

When a rolling body collides with a wall elastically,its torque is zero.But direction of velocity of particle is reversed.So will the angular momentum be conserved?
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How and why the acceleration of the ball during contact is different from $g$?

The Q is: My teacher said that the acceleration of the ball during the contact will be different from 'g' and therefore we have to treat the downward motion and upward motion separately . My ...
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1answer
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How can i find the velocities after the collision on this oblique collision problem [closed]

I found this excercise in my textbook but i couldnt finish it. Object $A$ with mass $m_1=m$ and velicity $u=12 m/s$ collides with object $B$ with mass $m_2=2m$ and velocity $u'=0$. After the ...
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How much energy is lost per bounce with a tennis ball? [closed]

When a tennis ball bounces it loses some energy. How much energy or height is lost per bounce?
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Do the balls keep moving forever?

In a hypothetical world where there is no friction, and all collisions are elastic would an object in lateral motion be perpetually moving and never come to a stop? Assumptions: Perfect vacuum: zero ...
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The impulse on a wall

If a ball was thrown to a wall, How could we calculate the impulse on the wall ? For example, if I throw a $2kg$ ball with $ 4m/s$, and it returned with the same speed but in the opposite direction, ...
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1answer
62 views

Is potential energy always inversely proportional to separation?

This is a question from Class 11 Physics NCERT. The answer is that only graph (v) is correct and the reason given here is that potential energy varies inversely with separation. But does that always ...
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Is there anything in the universe that cannot be compressed?

I've always thought that there is nothing in the universe that cannot be compressed or deformed under enough force but my friend insists that elementary particles are exempt from this. My thought is ...
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91 views

Change in momentum in Impulse of deformation and reformation

I was reading some text on coefficient of restitution when I encountered this , In the following you all would notice that in Impulse of deformation for particle $m_2$ we can see that change in ...
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2answers
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Is Kinetic energy always conserved in an elastic collision/impact?

While working out through some problems I encountered this problem : A ball moving with a velocity $v$ hits a massive wall moving towards the ball with a velocity $u$. An elastic impact lasts for ...
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1answer
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How does forward motion affect downward impact forces?

I like to skateboard fairly regularly and am also an avid watcher of the sport. Earlier I was watching this video where a skateboarder tears his MCL on a landing down an enormous drop. However, after ...
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Is reversal of velocity always equivalent to reversal of time?

Let us imagine there is a container full of small particles which are allowed to collide with each other and the container walls (in 2D). If I initialise the system with given velocities and positions ...
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Is “physical damage” proportional to momentum or kinetic energy? [duplicate]

If a rock is thrown at someone's head, or a car drives against a wall, or a meteor hits a planet, is the physical damage done to the object proportional to the projectile's momentum, or to its kinetic ...
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Can two black holes on a collision course, escape the merger?

Let's consider in this hypothesis that the two black holes have similar masses and approximation speed 0,99 c. At the maximum approximation point, only their event horizons are invaded slightly. The ...
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1answer
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Conservation of momentum — arm hitting object

Suppose I strike an object with my hand and I stop moving my hand as soon as I make contact with the object. This sends the object moving in a straight line with some velocity. Part 1: Is it valid to ...
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1answer
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Rigid body dynamics: modelling a polygon bounce off ground

I'm currently making a physics simulator, but I'm having some trouble making a polygon bounce off the floor. I know that collisions are normally modeled as described below by ja72, but I did it ...
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1answer
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Do all collisions (where the two bodies bounce away from each other) involve elastic deformation?

Does the stored potential energy in an elastic deformation provide the energy to push objects away from each other in all collisions when released, or only in certain cases like when striking golf ...
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Trajectories of a thrown object (with bumps considered)

Assume that I stood at the boundary line of a football / baseball / cricket ground(without any turf/pitch/grass in it) - just a plain ground - like play ground. I have a ball that can bounce when ...
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Why do the surfaces in contact of two colliding balls deform?

I've been told that it happens because the surfaces in contact must travel equal distances in any time interval as long as they are in contact. Could someone explain this in a different manner?
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Calculate Coefficient of Restitution when changing air pressure of a ball

Is it possible to calculate the coefficient of restitution using this formula, $$\text{coeff. of restitution }(e)=\dfrac {\text{relative velocity after collision}} {\text{relative velocity before ...
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How does particle size affect the elasticity of a collision between two particles?

Lets say two particles in an aerosol collide. How does the size of the particles help determine if the collision is elastic or inelastic? I am specifically referring to the following quote. It ...
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Bouncing ball physics

Do we generally ignore energy loss in kinematics when the ball ,falling under gravity , is bouncing back.Because below graph shows that Ball got the maximum velocity with which it was thrown earlier,...
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1answer
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The impact and collision principle

A particle P of mass 3m is moving in a straight line with speed u on a smooth horizontal table , a second particle Q of mass 2m is moving with speed 2u in the opposite direction of P on the same ...
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Energy Loss in Inelastic Collision

If we take a tennis ball and drop it from a certain height above the ground on earth, it collides inelastically, with the maximum height it can reach reducing after each collision due to loss of ...
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Coefficient of restitution in special relativity

It seems that all books about special relativity only include discussion about perfectly elastic and perfectly inelastic collisions. The notion of the coefficient of restitution, $e$ in classical ...
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Does throwing a penny at a train stop the train?

If I stand in front of a train and throw a penny at it, the penny will bounce back at me. For the penny to reverse its direction, at some point its velocity must go to zero. This is the point it hits ...
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Collision of particles [closed]

I read in a book that in both elastic and inelastic collision, the interacting forces after the collision become effecitively zero, the potential energy of the system remains the same both before and ...