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Old 04-17-08, 09:20 PM   #1
BenLi
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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...
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Old 04-17-08, 09:25 PM   #2
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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.
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Old 04-17-08, 09:41 PM   #3
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Oops!! Nerd Alert!!


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Old 04-17-08, 09:47 PM   #4
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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.
1. So what do you think this question is asking for?

2. Then, 1/16 of it is still there?
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Old 04-17-08, 09:54 PM   #5
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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.
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Old 04-17-08, 10:04 PM   #6
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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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Old 04-17-08, 10:30 PM   #7
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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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Old 04-17-08, 10:32 PM   #8
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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?
A: Peoria Illinois
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Old 04-17-08, 10:38 PM   #9
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A: Peoria Illinois
Damn, but you're good.
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Old 04-17-08, 11:08 PM   #10
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just look in the book. or ask the science help lab guys.
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Old 04-17-08, 11:20 PM   #11
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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
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Old 04-18-08, 04:58 AM   #12
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A: Peoria Illinois
Wordbiker, you and your Illinois Physics triggered an earthquake
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Old 04-18-08, 11:06 AM   #13
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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.
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Old 04-18-08, 05:03 PM   #14
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Private Message JSchen. He'll know.
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Old 04-18-08, 10:47 PM   #15
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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.
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Old 04-18-08, 11:46 PM   #16
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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.
Huh? F=ma, a=dv/dt, v is the integral of a.
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Old 04-18-08, 11:59 PM   #17
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Did you all hear that sound ?

That was my brain exploding.

Basic stuff.. yuh huh.
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