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OCR PHYSICS B G495~ 18th June 2015 AM ~ A2 Physics watch

1. (Original post by Minecraft27)
It's not mass because photons have no mass.
Have you not read my post? How can you argue with e=mc^2. Mass was definitely NOT conserved.
2. (Original post by Minecraft27)
Did anyone else write Charge for the thing that isn't conserved.

It's not quarks because there are no free quarks.
It's not mass because photons have no mass.
And I can't remember what the other thing was.

@post 295, a gamma photon was released too.
Can't be charge because there's the same number of protons present? Not nucleon number because nucleon number is constant. Can't be quark number.

Surely it's mass then. The mass of the products is lower because the mass defect has been converted to energy by E=mc^2 producing a gamma photon.

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3. (Original post by Minecraft27)
Shouldn't it have much much more?
Who knows?! What did you get the activity after 12 weeks as? ://
4. I also got another answer that was 3.17x10^-12 but I don't remember what question it was. Does this number seem familiar to anyone?
5. (Original post by HennersPD)
Who knows?! What did you get the activity after 12 weeks as? ://
12 weeks was 10.5 half lives so it's activity times by 1 over 2 to the power 10.5

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6. (Original post by HennersPD)
Who knows?! What did you get the activity after 12 weeks as? ://
379 Bq.
7. (Original post by STATER)
Have you not read my post? How can you argue with e=mc^2. Mass was definitely NOT conserved.
**** e=mc^2.

It's charge, because alpha particles have +2 charge and atoms are electrically neutral.
8. (Original post by Minecraft27)
**** e=mc^2.

It's charge, because alpha particles have +2 charge and atoms are electrically neutral.
The only thing that's charged is protons. Protons are the same on both sides so charge is conserved.

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9. (Original post by Rhetorical Hips)
12 weeks was 10.5 half lives so it's activity times by 1 over 2 to the power 10.5

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Wasn't the half life given as 8 weeks?
10. (Original post by Minecraft27)
I also got another answer that was 3.17x10^-12 but I don't remember what question it was. Does this number seem familiar to anyone?
yes
11. (Original post by STATER)
Wasn't the half life given as 8 weeks?
It was 8 days.

Atoms also have electrons round them which are negative charged. Alpha particles don't.
Atoms have electrons which cancel out the charge by protons, therefore as an alpha particle, it's positive charged.
12. (Original post by Rhetorical Hips)
12 weeks was 10.5 half lives so it's activity times by 1 over 2 to the power 10.5

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I did this and got it as 345 Bq as the initial activity was 5*10^5 Bq
13. (Original post by Minecraft27)
379 Bq.
sure it was 5*10^5 Bq was initial activity so i did this * 1/2^10.5 = 345 Bq
14. (Original post by gianamar)
yes
yes it does cannot remember what for though! there were 19 questions on that paper, most be a record for G495 haha!
15. (Original post by STATER)
Have you not read my post? How can you argue with e=mc^2. Mass was definitely NOT conserved.
I agree with you. Charge must be conserved in a nuclear reaction. The only thing on the list that couldn't be conserved was the mass.
16. (Original post by HennersPD)
sure it was 5*10^5 Bq was initial activity so i did this * 1/2^10.5 = 345 Bq
It depends what number you started with. I started with the answer I got which was 5.5 or something like that.

My answer led me to 379. I'm sure they'll allow it.
17. Anyone else get 0.89 grays?
18. I got 0.89 grays

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19. Am I the only person who feels that preparing for STEP probably cost a grade in this exam? I didn't prepare for physics as well as I should have because STEP was all consuming. Yesterday's nightmare called "STEP 2 the bloodbath" left my batteries dead.
20. (Original post by Minecraft27)
It was 8 days.

Atoms also have electrons round them which are negative charged. Alpha particles don't.
Atoms have electrons which cancel out the charge by protons, therefore as an alpha particle, it's positive charged.
You were not dealing with atoms, you were dealing with nuclei.

They're all positively charged, with a charge equal to the atomic numver

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