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Newton's 2nd Law

  1. Mar 23, 2010 #1
    Would the world fall apart and be destroyed if this law ceased to be constant? If not, how can we/do we speculate what would be different?

  2. jcsd
  3. Mar 23, 2010 #2
    Seems like a homework question.
  4. Mar 23, 2010 #3
    generally earth has some velocity.when it loss its path there is a chance to fll of world with out accelration.
  5. Mar 24, 2010 #4
    I am 33 years old and out of school. Homework is not part of my vocabulary now. So, do you have any answer besides this drivel?

    Not sure how this answers my OP?

    Anyone else ever think about this?
  6. Mar 24, 2010 #5


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    There are an infinite number of answers to this question. Instead of just saying, what if f=ma isn't true, you must additionally posit what IS true. Possibilities:
    F=mj (jerk)
    F=qa (charge)

    Etc. Each of these would lead to a very very different universe. Any specific ones you want to consider? Otherwise, the question is far too broad to give any answer at all.
  7. Mar 24, 2010 #6
    Great reply thanks.

    Here is a more direct question. Could the universe as we know it survive if the second law stopped working. I suppose it isn't the different equations I am interested, but more if the ones that are in place, like Newton's 2nd observation are absolute in a sense. That if they were not true, the universe could not exist.

    Anyway, hope that isn't still too vague. If so, sorry about that.
  8. Mar 24, 2010 #7
    It really depends on what you do with the equation (you can't just get rid of it, it is a simple statement about how much a massive object will accelerate under a force, unless you want to get rid of acceleration or something).

    Generally, things would be changed so much that there would be no way for anything like our universe to be around.
  9. Mar 24, 2010 #8


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    But newton's law already has stopped working, being in conflict with general relativity, and the world is still turning. Newton 2 says that I weigh 200 pounds (900 N or so for my SI friends) due to the mystical attractive 'force at a distance' that the earth exerts on me as caused by the acceleration of gravity. GR says that there is no such thing as a gravity force, rather, gravity is the curvature of spacetime in the presence of mass and energy. Newton 2 still gives a nice approximation, though.
  10. Mar 24, 2010 #9
    Thanks for mentioning GR, PhanthomJay. This is helpful.

    Great website from The American Museum of Natural History.
  11. Mar 24, 2010 #10
    OK, supposing that pre-Newtonian thought, where it was thought things that were bigger or heavier would travel faster than objects smaller or lighter. Would the universe still work in similar ways as it does now.

    I guess what I am getting at is, does the universe have to act in the way it seems to have acted for the last 13 billion years. Precisely in such a way, that if something deviated like a law, the universe would not have been possible?
  12. Mar 24, 2010 #11


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    Well, speaking of AMNH, and the 13 billion year history of the Universe, please watch this clip taking you on a journey to the beginning of time..then you decide....

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