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AQA Physics PHYA5 - Thursday 18th June 2015 [Exam Discussion Thread] Watch

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    (Original post by CD223)
    Probably - not quite sure where you're seeing them


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    Usually calculations.

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    This...


    Equating the two, as they're in thermal equilibrium gives:

    

0.250 \times 840 \times (T_f - 3) = 0.200 \times 4190 \times (30 - T_f)

    

\therefore T_f = 8.41 C^{o}


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    Don't tell only i see this

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    (Original post by a.a.k)
    Don't tell only i see this

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    Haha! That's so odd!

    Maybe the platform you're viewing it on doesn't support LaTex?

    Here's what it should look like!

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    Well thats weird. I was sooooo confused then i thought u might ve made smiley face might be a symbol to represent something.

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    (Original post by a.a.k)
    Well thats weird. I was sooooo confused then i thought u might ve made smiley face might be a symbol to represent something.

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    I can understand your confusion now!

    I wouldn't recommend using smileys in your proofs in the exam


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    (Original post by CD223)
    I can understand your confusion now!

    I wouldn't recommend using smileys in your proofs in the exam


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    Lol this is gold.

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    (Original post by CD223)
    In thermal equilibrium the cola reaches the same final temperature as the glass.

    In other words, the rise in thermal energy of the cola equals the fall in thermal energy of the glass.

    There is no net transfer of thermal energy beyond this point.

    Rise in thermal energy of the cola as it warms up from 3.0 degrees Celsius to the final temperature:
    

{\Delta Q_{Cola}} = {m_{Cola}} {c_{Cola}} (T_f - 3)

    Loss of thermal energy of the glass as it cools from 30 degrees Celsius to the final temperature:
    

{\Delta Q_{Glass}} = {m_{Glass}} {c_{Glass}} (30 - T_f)

    Equating the two, as they're in thermal equilibrium gives:

    

0.250 \times 840 \times (T_f - 3) = 0.200 \times 4190 \times (30 - T_f)

    

\therefore T_f = 8.41 C^{o}


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    Ahh I see. So they fall and raise by the same temperature. That's the part that confused me. As I figured that they'd fall and raise by a different amount, not the same amount of  T_f . As cola has a higher specific heat capacity, so I'd figure that'd warm up slower, due to requiring more energy. And the glass cool faster, due to less energy being required to change its temperature.
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    (Original post by dominicwild)
    Ahh I see. So they fall and raise by the same temperature. That's the part that confused me. As I figured that they'd fall and raise by a different amount, not the same amount of  T_f . As cola has a higher specific heat capacity, so I'd figure that'd warm up slower, due to requiring more energy. And the glass cool faster, due to less energy being required to change its temperature.
    Well they may lose and gain different amounts of thermal energy, but eventually they both reach a final temperature where there is no net transfer of thermal energy between the cola and the glass.

    If you think about it, the cola rises in temperature by a much smaller amount than the glass cools in temperature.



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    Hi,

    Do they expect us to know that the mass of a proton is 1.00728u because they just seem to use that in mark schemes but when I work it out with the data sheet I get 1,673x10^-27 / 1.661x10^-27 = 1.007224564. Can anybody explain how/where they get it from?

    Thanks
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    (Original post by samlyon)
    Hi,

    Do they expect us to know that the mass of a proton is 1.00728u because they just seem to use that in mark schemes but when I work it out with the data sheet I get 1,673x10^-27 / 1.661x10^-27 = 1.007224564. Can anybody explain how/where they get it from?

    Thanks
    Its in the data sheet look carefully in the list of values on first page then proton rest mass

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    (Original post by a.a.k)
    Its in the data sheet look carefully in the list of values on first page then proton rest mass

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    Ahhh, thank you
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    Anyone else leaving PHYA5 revision until after the PHYA4 exam now?


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    (Original post by CD223)
    Anyone else leaving PHYA5 revision until after the PHYA4 exam now?


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    Kind of

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    (Original post by CD223)
    Anyone else leaving PHYA5 revision until after the PHYA4 exam now?


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    I'm going to split it Saturday Sunday then concentrate on p4 Monday to Wednesday


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    (Original post by gcsestuff)
    I'm going to split it Saturday Sunday then concentrate on p4 Monday to Wednesday


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    Sounds sensible. I have too many exams around then to do that


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    Im leaving my physics unit 5 and chemistry unit 5 till after my first chemistry and physics exams

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    (Original post by Mai.H)
    Im leaving my physics unit 5 and chemistry unit 5 till after my first chemistry and physics exams

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    Me too. This exams seems ages away compared to PHYA4 lol.


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    (Original post by Master Sam)
    http://filestore.aqa.org.uk/subjects...1-QP-JAN13.PDF hey guys can anyone explain question 9 please, would greatly appreciate it! Correct answer is B
    You're on the wrong thread

    (Use this one next time: http://www.thestudentroom.co.uk/show....php?t=3047347)

    Here it is anyway!

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    (Original post by CD223)
    You're on the wrong thread

    (Use this one next time: http://www.thestudentroom.co.uk/show....php?t=3047347)

    Here it is anyway!

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Size:  117.4 KB


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    Thank youu
 
 
 
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