Energy and momentum.The misunderstanding have prevailed

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Homework Help Overview

The discussion revolves around the concepts of energy and momentum in the context of collisions, specifically involving train wagons and a bullet within a container. Participants are exploring the implications of conservation laws and the transformation of kinetic energy during collisions.

Discussion Character

  • Exploratory, Conceptual clarification, Assumption checking

Approaches and Questions Raised

  • Participants are questioning how heat can be generated without momentum in the context of collisions. There is a discussion about the conservation of momentum and energy, and how energy is transformed into heat and sound during impacts. Some participants are attempting to clarify the relationship between kinetic energy and momentum in different scenarios.

Discussion Status

The discussion is ongoing, with various interpretations being explored. Some participants have provided insights into the nature of particle motion and energy transformation, while others are seeking further clarification on these concepts. There is a recognition of the complexity involved in analyzing systems with multiple components.

Contextual Notes

Participants are grappling with the nuances of classical mechanics and the definitions of energy and momentum. There are references to historical disagreements among scientists regarding these concepts, and some participants express a desire for deeper understanding rather than rote memorization of methods.

Themistocles
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Energy and momentum.The misunderstanding has prevailed

Two train wagons of the same mass will impact.
Wagon A has velocity 10 and wagon B 0.When they impact a lock will make them conjoint.
Which will be the velocity of two wagons and which the energy after the collision;


We use the conservation of momentum (...not the energy)and we will find
that the velocity will be 5.We note that we have a loss of KE. AND we say with endless silliness and easiness that kinetic energy transformed to heat (and sound) :smile: the simple logic obey me to ask: <<<<<How the particles of the wagons have heat without momentum? Since all the momentum is visible to us, as velocity of the wagons.>>>>>>

All we know that must eventuate to the conservation of two quantums K.E. and P (for the most is only equations because of misunderstanding of the real meaning)

Type at google:{ James a Putnam Momentum and Energy} you will find a very helpfull article.
I think that few know their nescience , fewer know it, but can not do anything to learn ( ineffectual searching on books ,web).The people who know is the rarest.
I want to know the fundamental of physics like a scientist and no like accountant who has memorized the methods of solving problems and finish them automatically and ignores what the represent
Despite the previous i have a thought of the "two wagons" in the case of pendulum and bullet...

-We have answer of relativity that energy represents the matter.
-In 19th century scientists had disagreement of which of two quantums represent the element of difficulty to change velocity(see halliday and resnick book).Note that force is not the ordinary word ,people use ,it is a mathematical variable.Also they had engrossment how the same force to same object need different energy supplys depend of its different previous velocity.

If you have understand the collision of different mass object "in action-reaction level" the meaning of energy in classical mechanics
I please you to reply me or send me the adresses of the answers.Thanks of reading.Sorry if i have done language mistakes.
 
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Themistocles said:
<<<<<How the particles of the wagons have heat without momentum? Since all the momentum is visible to us, as velocity of the wagons.>>>>>>

The 'vibration' components of the particles' velocities, that result in heat energy actually cancel out, resulting in zero momentum due to heat. There are billions (much greater order actually) of particles where the probability of vibrating at any direction is the same.
 
ramollari said:
Mi pos file mporeis na to grapsis sta Agglika epidi ego dixtihos den eimai Elinas (spoudazo sti Elada) kai den to katalaveno sosta. Evxaristo.
c c
c b-> c
ccccccccccccc
We have a container and a bullet (of the same mass for easiness)
bullet is inside and has a speed from left to right.when it impacts to the right wall of the container ,it stops and the container now move.because practically we can not see inside the container or because the impact are continual and fastly we observe that the system moves constant with the half of course, speed.
 
So what's the problem? Momentum is conseved m1v1 + m2v2 = (m1 + m2)v
Overall energy is also conserved (Kinetic + heat + sound). Of course the kinetic energy of the system is decreased.
 
ramollari said:
So what's the problem? Momentum is conseved m1v1 + m2v2 = (m1 + m2)v
Overall energy is also conserved (Kinetic + heat + sound). Of course the kinetic energy of the system is decreased.
but we cannot separate the system.the system consists from the bullet and container .they have the quantums.And we want to examine exactly how the energy and momentum exists on it.Of course it is easily for us when the object is like a wooden pendulum which harmed by a bullet(complicated situation) to simplify the problem .ans say that energy went at heat and sound and ignoring how the particles have thermal-move without momentum.
i think your first reply is near the example of the container and bullet.
The essenetial is that if we don't want to conflict we must think of intermitent move of the system
 
We cannot take every single particle and compute its movement! Yet if we could, we would still get consistent results.
But it is more useful to abstract and view the system as two bodies where momentum is conserved and just say that the energy is lost as heat and sound, i.e. we take a more global perspective.
 

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