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The Physics PHYA2 thread! 5th June 2013 Watch

  • View Poll Results: What mark do you think you got out of 70?
    0-20
    6
    3.00%
    21-40
    12
    6.00%
    41-50
    29
    14.50%
    51-60
    79
    39.50%
    61-70
    74
    37.00%

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    (Original post by SortYourLife)
    Well you had the useful energy from the part before,

    So I took the power it gave you in the question (320kW?) and multiplied that by the time 55s so you'd have the energy supplied in that time


    Efficiency is useful/total * 100

    I got 22% (2sf)


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    I actually worked out the power in the gain in GPE by dividing that by 55 then working it out using the two powers. This gave the same answer of course
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    (Original post by .raiden.)
    I actually worked out the power in the gain in GPE by dividing that by 55 then working it out using the two powers. This gave the same answer of course
    yep that's how i did it
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    (Original post by .raiden.)
    I actually worked out the power in the gain in GPE by dividing that by 55 then working it out using the two powers. This gave the same answer of course
    Yeah I was thinking of doing that too aha, but hey same thing I used that to check my answer though


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    Just thought for that efficiency question, because you had to work out mass for the acceleration in the question before, did people use that mass, then multiplied by 9.81, or just use the 6500?

    Is this maybe why people are getting a range of answers? :s


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    In the exam say I got 6082.33456... For one answer and needed it in the next calculation, I would use all of it, is this okay?

    Eg for the first qeustion you get 6072.7524... Or something and so on

    I then used this in the second bit by doing 6072.7524... X the velocity they gave. Is this okay as it reduce rounding error?
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    (Original post by HenryD)
    Yeah I knew it had come up before and I could remember doing it so I was very happy.


    I think they're going to want a line of constant gradient up to T1, a sloping drop off as it decelerates in the oil and then a flat line to show terminal velocity (and then possibly a vertical line to 0 when it hits the bottom). Or, possibly a line which curves upwards into the flat if you want to argue that the ball would accelerate even in the oil which is unlikely but could be given.


    I'd think those marks will be around 94-96 UMS. With your Unit 1 I'd think you'll get an A overall.
    Ok! Thanks. One last thing.

    For question 1d?
    I got 3900000 for the potential energy. I have my answer as 3900000 and not in standard form. Will I still get the marks?
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    (Original post by Aarongreatbanks)
    In the exam say I got 6082.33456... For one answer and needed it in the next calculation, I would use all of it, is this okay?

    Eg for the first qeustion you get 6072.7524... Or something and so on

    I then used this in the second bit by doing 6072.7524... X the velocity they gave. Is this okay as it reduce rounding error?
    You should be fine, as the mark scheme usually gives the answer to 2sf but then also gives credit to answers using the calculator value. As long as you got 9.5 degrees for the angle and 9.2m/s/s for acceleration you should be fine.

    And yes you will receive credit for you answer if it isn't in standard form as the mark scheme says that 'answers not in standard form are not desirable but should not be penalised'.
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    (Original post by lebron_23)
    You should be fine, as the mark scheme usually gives the answer to 2sf but then also gives credit to answers using the calculator value. As long as you got 9.5 degrees for the angle and 9.2m/s/s for acceleration you should be fine.

    And yes you will receive credit for you answer if it isn't in standard form as the mark scheme says that 'answers not in standard form are not desirable but should not be penalised'.
    Ah ok, so I should get all the marks for the question where I put 3900000?
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    Hi for the density question, I used the volume of a sphere equation but I forgot to sqaure the radius but I did everything correct from there. How many marks will i get out of 3?
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    Also for the efficiency question to find the useful power I did Work done=force times distance and then divided it by 55 to get the power. Then divided by 320KW and times by a hundred. I got 24.5%. How many marks out of 3?
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    (Original post by Aarongreatbanks)
    Ah ok, so I should get all the marks for the question where I put 3900000?
    Yes, I don't see why you wouldn't get full marks on that.


    (Original post by pilotluke1)
    Hi for the density question, I used the volume of a sphere equation but I forgot to sqaure the radius but I did everything correct from there. How many marks will i get out of 3?
    Alas, I cannot say as I am not aware of the marking system that AQA have in place. Even the mark schemes for past papers are very vague. If, however, I were to hazard a guess, I would say you would get 2 out of the possible 4 marks, providing you stated your answer to an appropriate number of significant figures and you had all of the rest of the working correct.


    (Original post by pilotluke1)
    Also for the efficiency question to find the useful power I did Work done=force times distance and then divided it by 55 to get the power. Then divided by 320KW and times by a hundred. I got 24.5%. How many marks out of 3?
    Again, I cannot say, but most people on here seem to have got an answer that is roughly within that range, so I think you're fine.
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    (Original post by lebron_23)
    Yes, I don't see why you wouldn't get full marks on that.




    Alas, I cannot say as I am not aware of the marking system that AQA have in place. Even the mark schemes for past papers are very vague. If, however, I were to hazard a guess, I would say you would get 2 out of the possible 4 marks, providing you stated your answer to an appropriate number of significant figures and you had all of the rest of the working correct.

    Yeah I got an answer of 3677(or near there) and i rounded up to 3700. So is there is a mark for 2 sig figs?


    Again, I cannot say, but most people on here seem to have got an answer that is roughly within that range, so I think you're fine.
    Okay thanks
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    As ever, don't worry too much about significant figures. It's only worth marks on the one question per paper where an "appropriate number of significant figures" are asked for, where appropriate means same as in question, or plus one.

    http://filestore.aqa.org.uk/subjects...W-MS-JUN12.PDF
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    (Original post by Aarongreatbanks)
    Ok! Thanks. One last thing.

    For question 1d?
    I got 3900000 for the potential energy. I have my answer as 3900000 and not in standard form. Will I still get the marks?
    Yes

    (Original post by kingmango)
    Do you lose marks for significant figures in this exam?
    There's normally 1 question where it specifically asks you for the right number of SFs where you can be penalised, aside from that no not usually although I always show in my working the answer to multiple different SFs just in case.
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    (Original post by HenryD)
    Yes


    There's normally 1 question where it specifically asks you for the right number of SFs where you can be penalised, aside from that no not usually although I always show in my working the answer to multiple different SFs just in case.
    Also for the laser safety I said

    "Never shine the laser at someone's face or don't look alone the line of the laser beam and it would damage damage your eyes" is this okay for the 2 marks?
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    (Original post by Qari)
    Wasn't it 320kW?
    Probably, I can't remember :P But that was the method I used anyway.
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    Could someone link me to the post/thread with the unofficial mark scheme if possible please? Thanks
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    (Original post by NabRoh)
    Could someone link me to the post/thread with the unofficial mark scheme if possible please? Thanks
    Its in the first post
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    (Original post by Aarongreatbanks)
    Also for the laser safety I said

    "Never shine the laser at someone's face or don't look alone the line of the laser beam and it would damage damage your eyes" is this okay for the 2 marks?
    I would think so yes
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    Look against the finished UO mark scheme, I think I've got a minimum of 52 as that's taking marks off harshly e.g two marks off when I have three points for a 3 mark answer! I think of got a maximum of 56 so I have a range of 52-56 hopefully as I don't want to jinx it? Will this be a A considering January was a little easier and it was 50 for a A?
 
 
 
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