Elementary question on car crashes and momentum

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Discussion Overview

The discussion revolves around the concept of momentum in the context of car crashes, specifically addressing the apparent contradiction between the conservation of momentum and the observation that cars come to a stop after a collision. Participants explore the implications of momentum conservation and the factors affecting it, with a focus on theoretical understanding rather than specific case studies.

Discussion Character

  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • One participant questions where the momentum goes when two cars crash and come to a stop, suggesting that kinetic energy is transformed into damage but noting that this does not relate directly to momentum.
  • Another participant prompts for the initial momentum of the cars and the forces acting on them, indicating that these factors might influence the momentum during the crash.
  • Several participants express confusion about abstract concepts and the complexity of accounting for lost momentum, indicating a preference for concrete examples over theoretical discussions.
  • There is a suggestion to visualize the situation using vectors to clarify the momentum dynamics involved in the crash.
  • One participant notes that momentum conservation applies under specified conditions, hinting at the complexity of the scenario.

Areas of Agreement / Disagreement

Participants express varying levels of understanding and comfort with the abstract nature of the discussion. There is no consensus on how to approach the problem, with some preferring concrete examples while others suggest theoretical frameworks.

Contextual Notes

Participants have not reached a resolution regarding the relationship between momentum and kinetic energy in car crashes, and there are unresolved assumptions about the conditions under which momentum conservation applies.

Matt G
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When two cars crash into one another they generally come to a stop, yet we are told momentum cannot be created or destroyed. Where did their momentum go? It seems like the kinetic energy went into the damage in the vehicles but apparently that has nothing to do with momentum?.

Thanks Matt
 
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Can you write down their initial momentum? What forces are acting on the cars and what effect might they have on the momentum of the cars?
 
Sorry but it would just confuse me if I did. It seems like an abstract question and not one about a particular case
 
Google "momentum of an object" and it will help you see the relationship
 
Matt G said:
yet we are told momentum cannot be created or destroyed.
Under specified conditions.
 
Matt G said:
Sorry but it would just confuse me if I did. It seems like an abstract question and not one about a particular case
If you insist on accounting for the lost momentum, this is the most meangful way of doing it.
 
Draw it as vectors and it becomes clear...
 
Matt G said:
Sorry but it would just confuse me if I did. It seems like an abstract question and not one about a particular case
It may confuse you, but we can work through that. The point here is to help you solve the problem.
 

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