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  1. #1
    Hardrocker
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    Physics Help???? PLEASE!?!?!?!

    Alright, this is basic stuff, but I'm REALLY struggling with it, so if anyone could shed some light on these issues, it would be appreciated:

    1) Find the binding energy of N-13 nucleus, if the isotope of N-14 is more stable, what is the equation for the expected decay reaction.

    Okay so, for this question, I can get the binding energy part easily by using E=mc^2, but it's the latter part of the question I don't understand. We only learned about alpha, Beta (2 types), and gamma decay. None of those will get the N-13 to N-14

    2.) The half-life of N-13 is 10 min. If a sample contains 3.3 * 10^ 12 at t = 0, how many N-13 nuclei are still present 40 min. later?

    And this one... is just a blur...

  2. #2
    Senior Member
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    On #1, I don't think the question is asking what you think it is. N-13 can't decay to N-14 because N-14 has an extra neutron.

    On #2, the half life is exactly what it claims to be - the time after which half the stuff is still there. How many half lives have passed 40 min later, and what does that mean? Hint: if half of it is gone after 10 minutes, it does *not* mean it's all gone after 20.

  3. #3
    Hey guyz? Guyz? Wait up!! Siu Blue Wind's Avatar
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    Oops!! Nerd Alert!!


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    Please dont outsmart the censor. That is a very expensive censor and every time one of you guys outsmart it it makes someone at the home office feel bad. We dont wanna do that. So dont cleverly disguise bad words.

  4. #4
    Hardrocker
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    Quote Originally Posted by Mr. Underbridge View Post
    On #1, I don't think the question is asking what you think it is. N-13 can't decay to N-14 because N-14 has an extra neutron.

    On #2, the half life is exactly what it claims to be - the time after which half the stuff is still there. How many half lives have passed 40 min later, and what does that mean? Hint: if half of it is gone after 10 minutes, it does *not* mean it's all gone after 20.
    1. So what do you think this question is asking for?

    2. Then, 1/16 of it is still there?

  5. #5
    Senior Member deraltekluge's Avatar
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    I have no idea, myself, but a little googling (http://en.wikipedia.org/wiki/Nitrogen) tells me that Nitrogen 13 will decay to Carbon 13 via the emission of a positron.

    As Mr. Underbridge says, "half life" is the time it takes for half the atoms to decay. So, after 10 minutes, half the original atoms have decayed and half remain; after 20 minutes, half of those have decayed and a quarter of the original atoms remain; after 30 minutes, an eighth remain; and after 40 minutes, a sixteenth.

  6. #6
    Kicked out of the Webelos bluebottle1's Avatar
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    On the other hand, if a chicken and a half can lay an egg and a half in a day and a half, how long would it take a grasshopper with one wooden leg to kick all the seeds out of a dill pickle?
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  7. #7
    Footballus vita est iamlucky13's Avatar
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    Regarding #1, I think the statement that N-14 is more stable is just a hint that N-13 won't tend to reduce in neutrons while still remaining nitrogen. In other words, I think you can discount beta decay. And gamma decay isn't really a decay, it's a photon emission.

    Actually, looking up isotopes of nitrogen on wikipedia, this one has me slightly confused.
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  8. #8
    Pwnerer Wordbiker's Avatar
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    Quote Originally Posted by bluebottle1 View Post
    On the other hand, if a chicken and a half can lay an egg and a half in a day and a half, how long would it take a grasshopper with one wooden leg to kick all the seeds out of a dill pickle?
    A: Peoria Illinois
    Quote Originally Posted by ahsposo View Post
    Ski, bike and wish I was gay.

  9. #9
    Kicked out of the Webelos bluebottle1's Avatar
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    Quote Originally Posted by Wordbiker View Post
    A: Peoria Illinois
    Damn, but you're good.
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  10. #10
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    just look in the book. or ask the science help lab guys.

  11. #11
    Hardrocker
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    Thanks everyone, I think the consensus is that it's a Beta plus decay, my formula ended up looking like this

    n-13 -----> Carbon-13 + positron + neutrino

  12. #12
    The Site Administrator: Currently at home recovering from a couple of strokes,please contact my assistnt admins for forum issues Tom Stormcrowe's Avatar
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    Quote Originally Posted by Wordbiker View Post
    A: Peoria Illinois
    Wordbiker, you and your Illinois Physics triggered an earthquake
    on light duty due to illness; please contact my assistants for forum issues. They are Siu Blue Wind, or CbadRider or the other 3 star folk. I am currently at home recovering from a couple of strokes. I am making good progress, happily.


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  13. #13
    Pwnerer Wordbiker's Avatar
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    Quote Originally Posted by Tom Stormcrowe View Post
    Wordbiker, you and your Illinois Physics triggered an earthquake
    Yeah, that was a bit uncanny.

    I've never even been to Peoria...it just popped into my head. I was born in CA so I've been through my share of earthquakes. It's scary even when you're somewhat used to them.
    Quote Originally Posted by ahsposo View Post
    Ski, bike and wish I was gay.

  14. #14
    '05 NUEser EJ123's Avatar
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    Private Message JSchen. He'll know.

  15. #15
    1/2 man,1/2 bear,1/2 pig ManBearPig's Avatar
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    F does not equal MA. F equals M times the integral of dv/dt. It doesn't answer your question, but it's good to know for extra credit.
    ...

  16. #16
    Senior Member deraltekluge's Avatar
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    Quote Originally Posted by ManBearPig View Post
    F does not equal MA. F equals M times the integral of dv/dt. It doesn't answer your question, but it's good to know for extra credit.
    Huh? F=ma, a=dv/dt, v is the integral of a.

  17. #17
    Bicycle Repair Man !!! Sixty Fiver's Avatar
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    Did you all hear that sound ?

    That was my brain exploding.

    Basic stuff.. yuh huh.

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