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Homework Help: Forces between 2 down quarks could someone please help me : )

  1. Aug 31, 2010 #1
    Forces between 2 down quarks....could someone please help me : )

    Hi

    I am going slightly insane with this question I have!!!

    "A neutron contains two down quarks at a separation of approximately 10^−15 m. Calculate the strength in newtons of the electrical force between two down quarks at a separation of 1.0 × 10^-15 m."

    Now I have used F= k x (Q1 x Q2 / r (squared))

    so....

    F = 9 x 10^9 x ((1/3) x (-1.6 x 10^-19 C))(squared) / (1.0 x 10^-15 m )(squared)

    and I get 25.6 N

    Im pretty sure this is wrong, Im sure its much higher than that.

    Could anybody tell me where I am going wrong please.

    Thanks

    Danny
     
  2. jcsd
  3. Aug 31, 2010 #2

    Andrew Mason

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    Re: Forces between 2 down quarks....could someone please help me : )

    I agree with your answer. Why do you think it should be much higher? We are talking about something with an extremely small mass, so this force is really enormous.

    AM
     
  4. Aug 31, 2010 #3
    Re: Forces between 2 down quarks....could someone please help me : )

    Thanks for your reply,

    I am questioning my answer because the next question of my assignment says this....

    "Book 7 page 121 states that the strong force between two quarks ‘is equivalent to the weight of a 10-tonne truck’. Calculate the weight of a 10-tonne truck and compare this weight with the electrostatic force between the two down quarks in a neutron"

    Ive seen example questions which come out with an answer much much larger, but the examples didnt show working. Im really confused. Im pretty sure my figures are right, just not the answer. I am confuuuuused!
     
  5. Aug 31, 2010 #4

    Andrew Mason

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    Re: Forces between 2 down quarks....could someone please help me : )

    You were asked to find the electrostatic force between two quarks, not the nuclear force. The nuclear force between two quarks is much, much stronger. It is the nuclear force may be equivalent to the weight of a ten tonne truck.

    Furthermore, since the two down quarks have the same charge (-1/3 e) the force between them is repulsive, so it works against the nuclear force between them (which, like gravity, is attractive).

    AM
     
  6. Sep 1, 2010 #5
    Re: Forces between 2 down quarks....could someone please help me : )

    Ahhhhh ok, I think it has just become clearer to me now!!!!

    Thank you so much!

    Danny
     
  7. Aug 9, 2012 #6
    Re: Forces between 2 down quarks....could someone please help me : )

    Hi Danny, how was the feedbackt from your tutor to the previous two questions of your assignment? I am actually in your same position, trying to understand how the repulsive electric force of two down quarks could be compared to the weight (gravitational force) of a 10 tonne truck. Does anybody have any suggestion to add? Thanks!
     
  8. Aug 10, 2012 #7
    Re: Forces between 2 down quarks....could someone please help me : )

    Hey, I don't think I still have the feedback from this assignment, it was quite a while ago, but I shall have a look and get back to you if I find it.
     
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