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Homework Help: Energy and momentum in a car accident

  1. Dec 29, 2014 #1
    Two identical cars collide with equal and opposite velocity to each other. What happens to the energy? What happens to the momentum?

    Answer: energy is converted into heat and momentum disappears. But what has that to do with force?
     
  2. jcsd
  3. Dec 29, 2014 #2

    haruspex

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    Clearly forces are involved, but it can be hard to know exactly what they are at any given time in the collision process, and you don't need to care about that to answer the question.
    If you consider the force FA(t) that car A exerts on car B at time t, and the FB(t) that car B exerts on car A at time t, you can relate them. You can deduce something about momentum from that.
     
  4. Dec 30, 2014 #3
    There are two types of collisions, remember? Also, there is conservation of some quantity here...
     
  5. Dec 30, 2014 #4

    CWatters

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    I know what you mean but an fussy examiner might be more critical. Momentum is always conserved so how can it disappear?
     
  6. Dec 30, 2014 #5
    If you carefully consider the initial and final conditions, you'll understand.
     
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