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OCR Physics A G481 Mechanics [Thursday 17th May 2012]

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    (Original post by Mattyd951)
    Don't know why everyone got 2.6W for the spring one... I got 1.3W and I think (hope) that was right!
    The others I can remember were:

    11.8 degrees for the slope
    10m radius for the turbine
    27.3% efficient for turbine
    119Kg mass of the rider
    7.33m height of the ball
    59 degrees for the balloon angle
    From what I can remember I got all of those too, I thought that it was a fairly easy paper actually! Would love to see an unofficial mark scheme though.. I hope someone can get hold of the paper soon
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    how much is the Power question scored?
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    Less Kinematics than I was hoping for. Lots of easy questions and quite a few hard questions, not much in the middle. I reckon it will be a high grade to pass (+-50%) and a low grade to get an A. Maybe 42/43.
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    I left most of my answers to 2 s.f., will I lose marks? For instance, I left the mass as 120kg, the power as 1.3W, the percentage efficiency as 27% etc.

    Think I'll lose marks?

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    (Original post by Mattyd951)
    Don't know why everyone got 2.6W for the spring one... I got 1.3W and I think (hope) that was right!
    The others I can remember were:

    11.8 degrees for the slope
    10m radius for the turbine
    27.3% efficient for turbine
    119Kg mass of the rider
    7.33m height of the ball
    59 degrees for the balloon angle
    yeah same except got 2.6W which i think is wrong.
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    (Original post by .Username.)
    Does anyone reckon they got 53+
    Yes!
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    how much out of 60 should i get if i want 80/90 in UMS score?
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    About the angle question... How did everyone get 53 degrees????

    i thought net force up was 30
    18 to the right
    Tan= Opposite/ adjacent
    So i did inverse tan (18/30) and got 31 degrees?
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    (Original post by mack94)
    About the angle question... How did everyone get 53 degrees????

    i thought net force up was 30
    18 to the right
    Tan= Opposite/ adjacent
    So i did inverse tan (18/30) and got 31 degrees?
    I did exactly the same as u did
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    (Original post by Eric_lee)
    I did exactly the same as u did
    I think it wanted the angle to the horizontal though
    We worked out the angle the the verticle:mad:
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    One more question people as for the other angle question... How did everyone get 11.8??

    W sin(angle) = ma
    sin(angle) = a/g
    Inverse sin (3/9.81) = 17.8 degrees

    Either my methods wrong or my acceleration which i calculated to be 3 ms-2 is wrong.
    someone please help a brother out and tell me where i went wrong?
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    when can someone get hold of a paper and make a markscheme?? i getting really paranoid now
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    (Original post by mack94)
    One more question people as for the other angle question... How did everyone get 11.8??

    W sin(angle) = ma
    sin(angle) = a/g
    Inverse sin (3/9.81) = 17.8 degrees

    Either my methods wrong or my acceleration which i calculated to be 3 ms-2 is wrong.
    someone please help a brother out and tell me where i went wrong?
    The acceleration was 2.
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    (Original post by mack94)
    One more question people as for the other angle question... How did everyone get 11.8??

    W sin(angle) = ma
    sin(angle) = a/g
    Inverse sin (3/9.81) = 17.8 degrees

    Either my methods wrong or my acceleration which i calculated to be 3 ms-2 is wrong.
    someone please help a brother out and tell me where i went wrong?


    Acceleration is 2 ms^2
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    (Original post by mack94)
    I think it wanted the angle to the horizontal though
    We worked out the angle the the verticle:mad:
    sorry , i got a mistake. i got 59 degree of the angle from aretan(30/18)
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    yayayayay! I got 7.3 m for the height of the ball as well! Gaaah, so happy- thought I had completely bummed that question, well that's 2 0r 3 out of 60... woooh
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    I despair. My academic life is over.Not really but yeah.I despair.

    First question, I forgot to half the time so I got double the distance 14.7.How.Very.Idiotic.
    Then for the angle I got 11.8...but misread the followup question and ended dividing the force 510 by sin11.8x9.81(I thought wsin11.8=510)...I had worked out that the acceleration had become -4.29 but I thought this was too simple and crossed it out =/..wth,my silly brain.

    For the rockets when they are both fired, I said they remained in rotational equilibrium,at constant speed, no acceleration.sum of moments=0.
    And when only a was fired, the satellite gained momentum, and rotated clockwise.

    I need at least 85 Ums marks for it all to be an overall A.
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    (Original post by Charlottek12)
    From what I can remember I got all of those too, I thought that it was a fairly easy paper actually! Would love to see an unofficial mark scheme though.. I hope someone can get hold of the paper soon
    Aha, awesome! As long as someone else has got the same then it's all good!
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    I got all the way to finding the volume of of water, then to find the radius i used volume of a sphere by accident
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    wooh seeing these answers are making me feel better thought i did really bad... stupidly forgot stress and pressure had the same units pa though

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