Momentum in Inelastic Collisions

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    Collisions Inelastic
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Discussion Overview

The discussion revolves around the conservation of momentum in inelastic collisions, particularly in the context of a ballistic pendulum. Participants explore the conditions under which momentum is conserved, the implications of energy loss during collisions, and the effects of internal and external forces on momentum conservation.

Discussion Character

  • Exploratory
  • Technical explanation
  • Conceptual clarification
  • Debate/contested
  • Mathematical reasoning

Main Points Raised

  • Some participants assert that momentum is conserved during collisions because the forces involved are internal, while external forces can change momentum, as seen in the case of a pendulum.
  • Others argue that momentum can be applied to the ballistic pendulum by considering the collision phase separately, where momentum is conserved as the bullet embeds itself in the block.
  • A participant discusses the derivation of the momentum equation for inelastic collisions, emphasizing the importance of treating both masses as moving together post-collision.
  • Concerns are raised about energy loss during collisions and how it relates to momentum conservation, with some suggesting that momentum can be treated as conserved at the instant of collision despite energy losses.
  • Participants explore the concept of internal forces, such as friction and deformation, and how they do not affect the overall momentum of the system due to Newton's third law.
  • There is a discussion about whether momentum can be considered transferred instantaneously at the point of contact or if it should be viewed as a continuous process during the collision.

Areas of Agreement / Disagreement

Participants express differing views on the implications of energy loss during collisions and the treatment of internal versus external forces. There is no consensus on whether momentum can be treated as conserved throughout the entire collision process or only at the moment of impact.

Contextual Notes

Some participants note the limitations of their understanding regarding the assumptions made in momentum conservation, particularly in relation to external forces acting on the system and the nature of energy loss during collisions.

Who May Find This Useful

This discussion may be of interest to students and educators in physics, particularly those studying mechanics and the principles of momentum and energy in collisions.

  • #31
no I understand that part, but its not what I am talking about. I am talking about the interal forces that are exhanged during a collision.
 
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  • #32
Hmm, I have another question. How come we know that the area of the internal forces that take place during a collsion always sum up to be the same. I know that the two bodys experience the same force for the same amount of time, but what I am talking about is from one experiment to the next. Example, If i have a cetrain projectile inelastically collide with another, they will stick and move off together, and their momentum beore will be equal to that after. Now, let's say I have a heavier projectile but moving slower, so that the momentum is the same as in the first experiment, then they two will inelastically collide and move off together in the same direction with the same amount of momentum as when we started. Now according to the conservation of momentum, the area that is underneath both curves of forces for time in both experiments will be equal. My question is how do we know that they will be equal from one experiment to the next. My problem is that, if I were Newton and I said ok these have equal forces for equal amounts of time that would be acceptable for one case of an experiment. But this formula alone is not enough to let me conclude that for any other inelastic experiment of equal initial momentum will encouter the same area in the force curve. Is this something that was determined through experimentation, or was Newton able to say that friction plays no role in momentum exchange without ever having to do a single experiment?
 

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