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

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    (Original post by DomRauba)
    Astro : I got 3.0 m for the Diameter
    16,000 K for Black body temperature
    9.5 * 10 ^ 6 for Radius of the white dwarf
    4.9 * 10 ^ 17 for the Seconds
    -9.7 * 10 ^ -3 for Absolute Mag
    4 days for period , 1.1* 10 ^ 5 for speed

    Thermal : Density : 1.4 * 10 ^ 17
    RMS : 2.1 * 10 ^ (SOMETHING)
    Temperature : 320 Kelvins
    Energy : 4.7 *10 ^ 4 J ( I think )

    If anyone needs these
    I think my answers all agree
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    (Original post by 0beany0)
    why is everyone so happy i swear it wasn't THAT easy?!

    no clue for the 6 marker, though i could do the astro one
    thought it was a main sequence star
    got a different value for the magnitude
    lost like 4 marks somwehere else

    so thats like 16 marks lost...that i know of...

    could still be an a?
    People are over exaggerating, don't listen to them, expect around 58-62 for an A *
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    For the first tick box I put alpha, I was a bit unsure since it said X-ray as well, but out of alpha beta and gamma alpha is the most ionising.
    The the fill in the table I put 0.05 m for alpha and 2.0 m for beta.
    The the reason why the gamma count decreased I put about the inverse square law. Then for what affects alpha as on the human body, I put that the greatest hazard is, if it gets into your body as it can cause breaks in your DNA causing mutations. For the reason about alpha scattering I put that it says the same as they are just isotopes same number of protons but a different number of neutrons, and only the number of protons matters. Then for chain reaction said a neutron collides with a uranium nucleus releasing further neutrons which can cause another fission event. Then said the moderator slows down the neutrons released till they reach fissile speeds and can cause further fission reaction, and the moderator absorbs the neutrons KE, then said the casing of the reactor absorbs neutrons which cause the nuclei to become unstable and then emit beta- . and for the motion of the particles for the equation PV=1/3 Nm(Crms)^2 I put that they have random motion and do not collide with any of the other molecules in the container the mean square speeds squared them all added them together and divided by 3. Then for astro I did 2.57-1 and times by 1.50x10^11. then for the bit below did Tan(angle)=(diameter/distance) The tick box asking if it was a main sequence star, dwarf or a red giant I put a dwarf as it seemed quite small, and for the definition of black hole I said the escape velocity is greater than the speed of light.
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    (Original post by DomRauba)
    Astro : I got 3.0 m for the Diameter
    16,000 K for Black body temperature
    9.5 * 10 ^ 6 for Radius of the white dwarf
    4.9 * 10 ^ 17 for the Seconds
    -9.7 * 10 ^ -3 for Absolute Mag
    4 days for period , 1.1* 10 ^ 5 for speed

    Thermal : Density : 1.4 * 10 ^ 17
    RMS : 2.1 * 10 ^ (SOMETHING)
    Temperature : 320 Kelvins
    Energy : 4.7 *10 ^ 4 J ( I think )

    If anyone needs these
    Wasn't the abs magnitude 1.98(1) - M = 5log(25/10)
    Well **** that 1 I added changes it significantly, do you think they'll accept it?
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    (Original post by mrno1324)
    Wasn't the abs magnitude

    1.98(1) - M = 5log(25/10)
    Oh yeah. I did 1.982. Does it matter?
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    (Original post by Highlands)
    For the first tick box I put alpha, I was a bit unsure since it said X-ray as well, but out of alpha beta and gamma alpha is the most ionising.
    The the fill in the table I put 0.05 m for alpha and 2.0 m for beta.
    The the reason why the gamma count decreased I put about the inverse square law. Then for what affects alpha as on the human body, I put that the greatest hazard is, if it gets into your body as it can cause breaks in your DNA causing mutations. For the reason about alpha scattering I put that it says the same as they are just isotopes same number of protons but a different number of neutrons, and only the number of protons matters. Then for chain reaction said a neutron collides with a uranium nucleus releasing further neutrons which can cause another fission event. Then said the moderator slows down the neutrons released till they reach fissile speeds and can cause further fission reaction, and the moderator absorbs the neutrons KE, then said the casing of the reactor absorbs neutrons which cause the nuclei to become unstable and then emit beta- . and for the motion of the particles for the equation PV=1/3 Nm(Crms)^2 I put that they have random motion and do not collide with any of the other molecules in the container the mean square speeds squared them all added them together and divided by 3. Then for astro I did 2.57-1 and times by 1.50x10^11. then for the bit below did Tan(angle)=(diameter/distance) The tick box asking if it was a main sequence star, dwarf or a red giant I put a dwarf as it seemed quite small, and for the definition of black hole I said the escape velocity is greater than the speed of light.
    You are looking at a good grade my friend, first astro is wrong , I made the same mistake, you add 1 AU as largest distance is when its on the other side of the sun.
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    (Original post by CD223)
    Oh yeah. I did 1.982. Does it matter?
    It's how you read it of the graph, I assume there will be a range
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    (Original post by mrno1324)
    Wasn't the abs magnitude 1.98(1) - M = 5log(25/10)
    Well **** that 1 I added changes it significantly, do you think they'll accept it?
    Should do , there will be a range
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    (Original post by DomRauba)
    You are looking at a good grade my friend, first astro is wrong , I made the same mistake, you add 1 AU as largest distance is when its on the other side of the sun.
    So is everyone now agreeing that it is 2.57 + 1 because it said the asteroid belt thing is in between Mars and Jupiter I think.. or does that not matter?
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    (Original post by DomRauba)
    It's how you read it of the graph, I assume there will be a range
    2.27x10^17 for the number of nuclei question?
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    (Original post by Highlands)
    So is everyone now agreeing that it is 2.57 + 1 because it said the asteroid belt thing is in between Mars and Jupiter I think.. or does that not matter?
    hmm I have no idea, I done the same as you
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    (Original post by CD223)
    2.27x10^17 for the number of nuclei question?
    I got 2.35x10^17; seems pretty close, did you use your own value or the one given as show the decay constant blah blah.
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    (Original post by CD223)
    2.27x10^17 for the number of nuclei question?
    sounds familiar
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    F&//cking hell, did no one else do Pythagoras for first question? We're not told that the asteroid and the Earth are at opposite sides of the Sun at any one point.
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    (Original post by DomRauba)
    hmm I have no idea, I done the same as you
    Okay
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    (Original post by Doomlar)
    I got 2.35x10^17; seems pretty close, did you use your own value or the one given as show the decay constant blah blah.
    I think I used theirs.
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    (Original post by Bowenabc)
    Did you calculate it by taking 1 AU from 2.57AU (whatever the furthest distance was)

    or did you calculate it using a triangle with base 1 AU and legnth 2.57AU and take
    hypotenuse?
    The second option
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    (Original post by chizz1889)
    Yeah but in more detail eg:
    Pressure is directly proportional to temperature, measure the pressure for different temperatures and plot a graph of pressure against temperature. Plot a line of best fit and extrapolate backwards until it intercepts the x axis. This temperature is absolute zero. This is supported by the fact that for a fixed volume, P=kT where k is a constant, so when P = 0, T=0. This is because at this temperature the molecules have no kinetic energy so they don't vibrate and hence don't exert a pressure on the container. 😊 that's a six mark answer
    I did so blah lol i wrote in more detail, i said exactly the same word for word, except i didn't include extrapolate aha
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    (Original post by mrno1324)
    F&//cking hell, did no one else do Pythagoras for first question? We're not told that the asteroid and the Earth are at opposite sides of the Sun at any one point.
    So what's your point?? Using Pythagoras would assume the same thing...


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    (Original post by lad123)
    I did so blah lol i wrote in more detail, i said exactly the same word for word, except i didn't include extrapolate aha
    Yeah you should get 6 then 😝
 
 
 
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