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    Does anyone have the jan 2010 unit 5 paper and mark scheme ?
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    (Original post by AdamThePhysicsMo)
    Does anyone have the jan 2010 unit 5 paper and mark scheme ?
    Sorry, there isn't one - unit 5 was first examined in June 2010.
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    (Original post by 16characterlimit)
    Does anyone know if I can get by with saying 1 light year is 3x10^8 * 60*60*24*365.25 ?

    And 1 AU is 3x10^8 * 60 * 8

    Or do I have to remember them.
    And does anyone know a good way of remember parsec to light year conversion, 3.26 right?
    I know that 1 light year is easy to calculate, but I have never seen a question in which you have to calculate 1 AU. Could you send me one?
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    What are the materials that control rods and nuclear reactors are made out of?
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    (Original post by 16characterlimit)
    What are the materials that control rods and nuclear reactors are made out of?

    Control Rods: Cadmium and Boron.
    And about Nuclear Reactors, you are asking about like what components it's made of?
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    (Original post by sabahshahed294)
    Control Rods: Cadmium and Boron.
    And about Nuclear Reactors, you are asking about like what components it's made of?
    Not sure, I think it was Carbon or something,but you needed to remember Boron control rods and the material of something else in the reactor.
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    (Original post by 16characterlimit)
    Not sure, I think it was Carbon or something,but you needed to remember Boron control rods and the material of something else in the reactor.
    That's the moderator you are talking about. Moderator is used to slow down fast moving neutrons.
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    (Original post by sabahshahed294)
    That's the moderator you are talking about. Moderator is used to slow down fast moving neutrons.
    That's the one, thanks.
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    (Original post by 16characterlimit)
    That's the one, thanks.
    Np.
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    Does anyone know what Edexcel deems the correct penetrative properties for each radiation?

    Alpha can't get through paper?
    Gamma needs thick lead?

    I never know if Beta can or cannot go through a this aluminium sheet.
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    (Original post by 16characterlimit)
    Does anyone know what Edexcel deems the correct penetrative properties for each radiation?

    Alpha can't get through paper?
    Gamma needs thick lead?

    I never know if Beta can or cannot go through a this aluminium sheet.
    Some beta may be able to get through a very thin sheet of aluminium. Gamma cannot be fully stopped, though for convenience we say that a considerable amount of led will reduce the gamma to ≈ 0.
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    (Original post by mrbeady9)
    Some beta may be able to get through a very thin sheet of aluminium.
    Your picture says the opposite..?
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    (Original post by 16characterlimit)
    Your picture says the opposite..?
    "Although the beta particles given off by different radioactive materials vary in energy, most beta particles can be stopped by a few millimeters of aluminium."

    Source: https://en.wikipedia.org/wiki/Beta_particle
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    (Original post by mrbeady9)
    "Although the beta particles given off by different radioactive materials vary in energy, most beta particles can be stopped by a few millimeters of aluminium."

    Source: https://en.wikipedia.org/wiki/Beta_particle
    So what would you put in an exam.
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    (Original post by 16characterlimit)
    So what would you put in an exam.
    I would usually refer to the table attached, which was in an exam question.
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    Name:  Screen Shot 2016-06-25 at 20.00.15.png
Views: 90
Size:  109.1 KBPlease could you explain how to get to the answer for this question.

    Correct Answer:
    Spoiler:
    Show
    A
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    (Original post by CasioGamer98)
    Name:  Screen Shot 2016-06-25 at 20.00.15.png
Views: 90
Size:  109.1 KBPlease could you explain how to get to the answer for this question.

    Correct Answer:
    Spoiler:
    Show
    A
    I think it's A because of this reason that nitrogen is heavier than helium so mass is inversely proportional to speed. So, greater the mass, lower the speed.
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    (Original post by sabahshahed294)
    I think it's A because of this reason that nitrogen is heavier than helium so mass is inversely proportional to speed. So, greater the mass, lower the speed.
    Thanks for that. Thats the only explanation I had for their answer too but it still doesn't make sense. Only I thought because it doesn't say there's the same number of molecules in each sample you could increase the number of molecules of helium beyond the number in the nitrogen sample so it has a larger mass than the nitrogen sample. This would then create a circumstance where it had equal or smaller mean square speed as <c^2> = 3kT/m so if T is constant as stated in the question, increasing m will alter the <c^2>.

    It's probably just me always reading way to far into a question loosing me easy marks! But can you spot a mistake with my logic?

    Ok i've worked out where my logic is wrong. It's because m in the equation refers to the mass of an individual molecule, not an entire sample. Hence it's as simple as you say where greater mass causes lower speed. Thanks!
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    (Original post by CasioGamer98)
    Thanks for that. Thats the only explanation I had for their answer too but it still doesn't make sense. Only I thought because it doesn't say there's the same number of molecules in each sample you could increase the number of molecules of helium beyond the number in the nitrogen sample so it has a larger mass than the nitrogen sample. This would then create a circumstance where it had equal or smaller mean square speed as <c^2> = 3kT/m so if T is constant as stated in the question, increasing m will alter the <c^2>.

    It's probably just me always reading way to far into a question loosing me easy marks! But can you spot a mistake with my logic?
    Increasing the number of molecules will not have any effect actually. By mass, they mean mass of the atom or molecule and not the mass of the whole sample. It is mainly temperature and since in this case, temperature remains same. Mass will play a role in the effect
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    (Original post by CasioGamer98)
    Thanks for that. Thats the only explanation I had for their answer too but it still doesn't make sense. Only I thought because it doesn't say there's the same number of molecules in each sample you could increase the number of molecules of helium beyond the number in the nitrogen sample so it has a larger mass than the nitrogen sample. This would then create a circumstance where it had equal or smaller mean square speed as <c^2> = 3kT/m so if T is constant as stated in the question, increasing m will alter the <c^2>.

    It's probably just me always reading way to far into a question loosing me easy marks! But can you spot a mistake with my logic?

    Ok i've worked out where my logic is wrong. It's because m in the equation refers to the mass of an individual molecule, not an entire sample. Hence it's as simple as you say where greater mass causes lower speed. Thanks!
    Ah sorry I was away for work lol. Saw after answering
 
 
 
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