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Violated Newton's third law

  1. Dec 20, 2005 #1
    What would happen if (if ever) when the action force is greater than or less than the reaction force and were not equal in magnitude and were not equal in size?
  2. jcsd
  3. Dec 21, 2005 #2


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    Momentum would not be conserved ; which would translate into physics not being invariant under translations in space.
  4. Dec 21, 2005 #3
    Well, that depends on your understanding of what is contact. Two objects in contact due to force exert equal and opposite force to each other so that they remain in contact. The third law is just a continuation of this concept and is not an independent law. But it is simply surprising that this also applies on two remote objects which are not in contact if the considered force is gravitational or electrostatic of distant objects.
  5. Dec 21, 2005 #4

    Doc Al

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    What do you mean? Are you implying that as long as the 3rd law is satisfied, two objects must remain in contact?
  6. Dec 21, 2005 #5
    I mean that is esential for two objects to remain in contact. Correct if I am wrong
  7. Dec 21, 2005 #6

    Doc Al

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    Two objects that come into contact will exert equal and opposite contact forces on each other in accordance with Newton's 3rd law. It doesn't matter whether they remain in contact with each other or separate; Newton's 3rd law is satisfied either way.
  8. Dec 21, 2005 #7
    force either comes in magnitude or in size , not both.
  9. Jan 25, 2006 #8
    Another question; what if the forces in newton's third law were not equal for things like running, throwing, jumping, lifting, kicking, punching, squeezing, stretching and breaking?
  10. Jan 25, 2006 #9


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    Netwon's Laws merely describe how we see the world work. They do not have anything to do with why they work like that.

    I suspect what you want to propose is something like: what if an object's inertia managed to drop to zero? What would happen?
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