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Newton's law conceptual question

  1. May 4, 2009 #1
    1. The problem statement, all variables and given/known data[/b]
    The force you exert on the earth is insignificant compared to the force the earth exerts on you. (True or false)

    The attempt at a solution[/b]

    I believe that this is false based upon Newton's third law--shouldn't the forces be equal and opposite?


    2. Ice cube floating in glass of water--water level increases when it melts.

    Is this also false? Unless the ice cube is being held under the water, shouldn't the density and volume differences cancel out since the mass does not change? (Assuming the ice is chemically identical to the water?)
     
  2. jcsd
  3. May 4, 2009 #2
    I believe that this is false based upon Newton's third law--shouldn't the forces be equal and opposite?

    I believe You're right.

    about the second question , I don't want to say something wrong, so You'll have to wait some 1 else .
    but I think you're right here as well
     
  4. May 4, 2009 #3
    You are right at 2, too. At yes, that is the right way of thinking.
     
  5. May 4, 2009 #4
    Thank you both!!
     
  6. May 4, 2009 #5

    tiny-tim

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    Welcome to PF!

    Hi riverjib! Welcome to PF! :smile:
    Yup! :biggrin:
    Yup again!

    (but mention the law specifically: water displaced equals … ?)

    That's why sea-level doesn't rise when floating ice in Antarctica melts. :wink:
     
  7. May 4, 2009 #6
    Thanks Tim :smile:
    I'm glad I found this forum!!
     
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