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Question about analyzing forces

  1. Mar 1, 2012 #1
    In a try to test my knowledge of Newton's laws, I have posed the following question to myself.

    My attempt:

    (The arrows indicate direction.)

    I have been informed that the solution is invalid, and that the question itself is wrong. Can you tell me why the problem is wrong/invalid?
    Someone tried to explain to me, but I didn't really understand.
  2. jcsd
  3. Mar 1, 2012 #2

    Doc Al

    User Avatar

    Staff: Mentor

    For one thing:
    This contradicts Newton's 3rd law.

    A and B will exert equal and opposite forces on each other.
  4. Mar 1, 2012 #3
    Thanks for the simple answer.
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