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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 StalkeR47)
    No idea m8. We will see what happens.
    I can only think of one specific mistake I made, and that's not lowering the intensity on the graph... I think i'll possibly lose a maximum of another 5-10 marks?
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    (Original post by SNR)
    I'm seriously relying on ecf marks, half the time I got the method right for the follow on question but the initial one was off the chart of wrongness.



    Unit 1: got 60.
    Unit 2: anywhere from 29 to 40, it's a good job Gove hasn't banned resits yet.
    You can only resit in june from now on. But, I am not going to resit for sure.
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    I think it will be around 58/59 for an a in this paper 100% ums 68/70
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    Does anyone know how many marks were for the ball graph question and the intensity graph question? I think I rushed and flustered both.
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    (Original post by Bookaky)
    I think it will be around 58/59 for an a in this paper 100% ums 68/70
    That prediction has a little subjectivity in it. More likely 52 for A 62 for 100
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    (Original post by lebron_23)
    PHYA1 (Provisional, and very shaky) Mark scheme;

    Question 1 – Simple matter of working out forces and that stuff, efficiency question may cause problems though.

    1) 6082N, which is 6100 to 2sf
    b) 9.5 degrees using arctan of 1000/6000
    c) Acceleration was 9.2ms^-2
    d) Can’t remember what this one was asking but I got 3.9x10^6 (not sure)
    e) I got 20.5% but I’m not sure as I’ve heard people give various answers

    Question 2 – Fairly straightforward question about projectiles.

    2) Time taken was 0.55s
    b) The horizontal distance was 248m I think
    c) As both bullets have the same mass, S=ut will be smaller for the bullet with the lower horizontal velocity
    -- Can’t remember if there was anything more to this question

    Question 3 – Perhaps the best 6 marker they’ve ever given, very straightforward.

    3) The ball begins to accelerate with a large acceleration as its weight force is (one of) the only forces acting as it begins to move. The gradient then begins to slowly decrease as the resistive forces begin to balance out the weight force. The ball finally reaches terminal velocity as the resistive forces balance out the weight force. Appropriate reference to Newton’s first law needed. Then the ball remains at that velocity, as there is no external force, give reference to Second Law.
    b) Initially a straight line indicating uniform acceleration, then a curve of decreasing gradient ending with the ball at terminal velocity.

    Question 4 – A decent question, I guess.

    4) Hooke’s law states that force applied is proportional to the extension up to the limit of proportionality
    b) Gradient was roughly 1150/1100 Nm^-1needed
    c) Using the area of a triangle and then counting (roughly) 9 small boxes each of area 0.025 gave 1.08J
    d) Straight line parallel to the first one but not finishing at zero as plastic deformation has occurred
    d) Plastic deformation means the object won’t return to its original shape/length once the load is removed
    d) Work is less as area under graph is less energy absorbed as heat and in permanent extension

    Question 5 – Wasn’t too bad..

    5) Two conditions for TIR were an angle greater than the critical angle and moving from a medium of higher refractive index to lower
    b) Defining the frequency of a progressive wave. Just explain the equation?
    c) Speed of light in the object thing was 1.7x10^8
    d) Proof that the angle was about 31.8 degrees using Snell’s Law
    e) Critical angle was 51.1 degrees using 1/sinc
    f) Undergoes TIR as (20+31.9) > 51
    e) TIR drawn (not sure about this one and the one above)

    Question 6 – Don’t even know, seemed cool..

    6) First phase difference was 90 degrees or pi/2. Second was 270 degrees or 3pi/2
    b) Oscillation between maximum and minimum amplitude; i.e moves up and down
    c) Polarisation only occurs in transverse waves; mention something about plane of polarisation
    d) Define frequency
    e) 750m

    Question 7 – I may have flopped :eek:

    7) All of the light has the same wavelength
    b) Can’t really remember – According to Frogs491 its ‘Fringes larger so intensity equal’
    c) I too cannot seem to remember this
    e) Last part; white at central maxima and very bright as all of the wavelengths converge at the centre; blue tinge closer to central maxima and red tinge further away; not sure about anything else.

    That’s all I can remember guys. I’ve probably omitted quite a few things so if anyone can spot any mistakes, let me know and I’ll make amendments
    6) I'm not too sure about, people I knew were throwing out 180 out of phase and inphase, I thought it'd be 270 out of phase but I'm not really sure if I'm right or not.
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    (Original post by Bookaky)
    I think it will be around 58/59 for an a in this paper 100% ums 68/70
    Nope! You have a very high grade boundary predictions. Normally, it is 48 or an A and this paper for definitely harder than normal so grade boundary will be lower than 48 for sure. Around 46-44/70 I recon.
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    (Original post by Bookaky)
    I think it will be around 58/59 for an a in this paper 100% ums 68/70
    Based on what evidence?


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    For the graph about the ball and the oil I think it is debatable. Surely the ball would continue to accelerate in the oil for only a short period of time and then level off for terminal velocity?
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    (Original post by PodgyBoy)
    Does anyone know how many marks were for the ball graph question and the intensity graph question? I think I rushed and flustered both.
    The velocity/time graph was 3 marks and the intensity graph was 2 marks.
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    (Original post by StalkeR47)
    I think I got about 57 marks in unit 2 (under estimated) and about 65 marks in unit 1( under estimated). What do people think what you got in unit 1 and 2?
    Lets not go boasting haha at the very least 59/70 in unit1 and 53/70 in unit2. I am the master of making stupid mistakes I always walk out the exam room and realise what i've done wrong
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    (Original post by lebron_23)
    PHYA1 (Provisional, and very shaky) Mark scheme;

    Question 1 – Simple matter of working out forces and that stuff, efficiency question may cause problems though.

    1) 6082N, which is 6100 to 2sf
    b) 9.5 degrees using arctan of 1000/6000
    c) Acceleration was 9.2ms^-2
    d) Can’t remember what this one was asking but I got 3.9x10^6 (not sure)
    e) I got 20.5% but I’m not sure as I’ve heard people give various answers

    Question 2 – Fairly straightforward question about projectiles.

    2) Time taken was 0.55s
    b) The horizontal distance was 248m I think
    c) As both bullets have the same mass, S=ut will be smaller for the bullet with the lower horizontal velocity
    -- Can’t remember if there was anything more to this question

    Question 3 – Perhaps the best 6 marker they’ve ever given, very straightforward.

    3) The ball begins to accelerate with a large acceleration as its weight force is (one of) the only forces acting as it begins to move. The gradient then begins to slowly decrease as the resistive forces begin to balance out the weight force. The ball finally reaches terminal velocity as the resistive forces balance out the weight force. Appropriate reference to Newton’s first law needed. Then the ball remains at that velocity, as there is no external force, give reference to Second Law.
    b) Initially a straight line indicating uniform acceleration, then a curve of decreasing gradient ending with the ball at terminal velocity.

    Question 4 – A decent question, I guess.

    4) Hooke’s law states that force applied is proportional to the extension up to the limit of proportionality
    b) Gradient was roughly 1150/1100 Nm^-1needed
    c) Using the area of a triangle and then counting (roughly) 9 small boxes each of area 0.025 gave 1.08J
    d) Straight line parallel to the first one but not finishing at zero as plastic deformation has occurred
    d) Plastic deformation means the object won’t return to its original shape/length once the load is removed
    d) Work is less as area under graph is less energy absorbed as heat and in permanent extension

    Question 5 – Wasn’t too bad..

    5) Two conditions for TIR were an angle greater than the critical angle and moving from a medium of higher refractive index to lower
    b) Defining the frequency of a progressive wave. Just explain the equation?
    c) Speed of light in the object thing was 1.7x10^8
    d) Proof that the angle was about 31.8 degrees using Snell’s Law
    e) Critical angle was 51.1 degrees using 1/sinc
    f) Undergoes TIR as (20+31.9) > 51
    e) TIR drawn (not sure about this one and the one above)

    Question 6 – Don’t even know, seemed cool..

    6) First phase difference was 90 degrees or pi/2. Second was 270 degrees or 3pi/2
    b) Oscillation between maximum and minimum amplitude; i.e moves up and down
    c) Polarisation only occurs in transverse waves; mention something about plane of polarisation
    d) Define frequency
    e) 750m

    Question 7 – I may have flopped :eek:

    7) All of the light has the same wavelength
    b) Can’t really remember – According to Frogs491 its ‘Fringes larger so intensity equal’
    c) I too cannot seem to remember this
    e) Last part; white at central maxima and very bright as all of the wavelengths converge at the centre; blue tinge closer to central maxima and red tinge further away; not sure about anything else.

    That’s all I can remember guys. I’ve probably omitted quite a few things so if anyone can spot any mistakes, let me know and I’ll make amendments
    I didn't mean so intensity equal but Red light is just a higher wavelength of light therefore diffracts more no intensity changes should occur the maxima and minima should just be more spread out. Don't take my word on it though ill have to check about intensity can't see any reason it would change though

    sorry if its a little weird in set up
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    (Original post by FLLF)
    Constant positive gradient until it hits the oil, then it slopes off downwards sharply, and levels off to a constant speed before hitting the bottom
    oh okay, thanks
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    (Original post by Raimonduo)
    6) I'm not too sure about, people I knew were throwing out 180 out of phase and inphase, I thought it'd be 270 out of phase but I'm not really sure if I'm right or not.
    Its 270 (2π x 3/4 = 270)
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    (Original post by Frogs491)
    I didn't mean so intensity equal but Red light is just a higher wavelength of light therefore diffracts more no intensity changes should occur the maxima and minima should just be more spread out. Don't take my word on it though ill have to check about intensity can't see any reason it would change though
    Intensity DOES decrease because it diffracts further away than what blue light did central maxima is wider but the light diffracts more
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    (Original post by posthumus)
    Third time sitting this & I've sat unit 1 twice... I think it's the hardest AS module I've sat
    i was happy with the 6 marker especially, but the first 2 pages were really tricky
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    Raimondo, for the frequency you didnt have to explain the equation but simply define frequency which is the number of times the progressive wave passes a given point per second
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    (Original post by Frogs491)
    I didn't mean so intensity equal but Red light is just a higher wavelength of light therefore diffracts more no intensity changes should occur the maxima and minima should just be more spread out. Don't take my word on it though ill have to check about intensity can't see any reason it would change though

    sorry if its a little weird in set up
    This graph is drawn in the nelson thornes book. I can not remember what page. Check. They have 3 curves. 2 red and 1 blue.
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    (Original post by Mr.Suhk)
    The graph was wider and lower in intensity:

    intensity is the energy of photons: E= hc/wavelength therespre increasing wavelength decreases energy which decreases intesity.

    Thats what my teacher told me.
    Yes the photon energy decreases, but light intensity is the number of photons arriving at a point per second. Remember the photoelectric effect? Increasing the intensity increases the number of photon emitted per second as more photons are arriving per second. The energy of the photon just dictates the kinetic energy of the photos. Thus, the same number of photons of red and blue light arrive per second regardless of their energies. Thus the intensities are equal regardless.
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    So people stressing over makes, what do you guys want to do at uni?
 
 
 
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