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Hmmmm... Physics Paper, how was it for you?

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    #122
    The Walsho
    Registered Users Posts: 1,251 ✭✭✭The Walsho


    I know this is silly but did anyone else get the sense it was a back-up paper?
    Experiments were way off what I had predicted, and the logo on the front of the paper was coloured differently, and all those mistakes! Really silly errors they were. Probably just me though.

    Anyway, I got on okay with the paper, but still probably one of my worst exams. I left out electricity for the experiments, along with one of the mechanics experiments. Guess which mechanics I left out? That's right, the pendulum one.

    Anyway, finished the Leaving Cert!

    What the hell do I do now?


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    #123
    Peleus
    Registered Users Posts: 784 ✭✭✭Peleus


    YellowRabbit wrote: »
    For the how many times does the astronaut see the sunrise thing, i got 15.4, but surely as .4 of a day is up until 9'oclock, he still would have seen the sixteenth sunrise even if it's not a whole number?

    Overall I thought the paper was fair enough.

    I got 14 pions too.

    the worst thing you can do is think about it too much! the examiner hardly expects you to write: "It would be fifteen assuming he started at midnight but 16 if it started at 9pm and would be 17 if that year was a leap year but would only be fifteen if the the day was the 29th of February or if the rate of the Universe's expansion increased..."

    you just divide the period into 24 hours (in seconds). and you get 15.42 which is 15. simple as.


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    #124
    nyangnyang
    Closed Accounts Posts: 40 ✭nyangnyang


    Ally_ally wrote: »
    i'm the exact same!!!!! it's sooooo annoying! that stupid q1 and q3...i attempted 1 but graph was all wrong...id say i got about 3 out of 4o...seriously!

    LMAO,1 and 3 were the ones i couldn't do as well and I also tried the graph on q1 and also got it wrong. Great minds and terrible minds think alike!!:D


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    #125
    Sugarplum_fairy
    Closed Accounts Posts: 35 ✭Sugarplum_fairy


    for the fluorescent bulb thing i said it was efficient cause it took non-visible uv, and because of the fluorescence turned it into visible white light.

    and for the movement of electrons thing in q7 i talked about the energy level, it jumps up one then falls back and emits a photon of light.

    i did one extra q, but unfortunately messed up my q6 and q10, so hopefully one of them will be messed not too badly


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    #126
    Parsley
    Closed Accounts Posts: 3,144 ✭✭✭Parsley


    Went grand for me, probably my best exam. Got exactly 9.81 m/s^2 for g. :D
    Q5 20,000pa for the thumbtack.
    Q7 Resistivity of nichrome - 1.14x10^-6, heat generated by toaster - 120960
    Q8 .01s, .02 Webers and -2v.
    Q11 Change in momentum - 5.4,2.178x10^-19 for the energy of the photon, 1.111x10^-9 for the mass
    Q12a 32.2 for distance, 5.42m for height
    b 423.29 or 211.65 for doppler, depending on how the wording is interpretted.


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    #127
    Stevieo
    Closed Accounts Posts: 63 ✭✭Stevieo


    For the toaster question I struggled to find 3 precautions, seeming as it was 9 marks, so aside from the Earth wire, I wrote to use plastic protection and put warning stickers on the toaster. Deary deary me......

    Somebody please: Question 11, golf ball and Newton's Laws part. Explain bitte!


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    #128
    Cokehead Mother
    Closed Accounts Posts: 773 ✭✭✭Cokehead Mother


    Stevieo wrote: »
    For the toaster question I struggled to find 3 precautions, seeming as it was 9 marks, so aside from the Earth wire, I wrote to use plastic protection and put warning stickers on the toaster. Deary deary me......

    Somebody please: Question 11, golf ball and Newton's Laws part. Explain bitte!

    F = ma

    F = (mv - mu)/t

    mv - mu = change in momentum = Ft


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    #129
    Stevieo
    Closed Accounts Posts: 63 ✭✭Stevieo


    But if you're not given the mass of the golf ball or club....?


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    #130
    Cokehead Mother
    Closed Accounts Posts: 773 ✭✭✭Cokehead Mother


    Stevieo wrote: »
    But if you're not given the mass of the golf ball or club....?

    You don't need it.

    You just need to find the change in momentum, which is mv - mu. It doesn't matter what m, u and v actually are.


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    #131
    Stevieo
    Closed Accounts Posts: 63 ✭✭Stevieo


    Simultaneous equations is it? Darrrrn....I thought of that.


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    #132
    Cokehead Mother
    Closed Accounts Posts: 773 ✭✭✭Cokehead Mother


    Stevieo wrote: »
    Simultaneous equations is it? Darrrrn....I thought of that.

    Noooo

    The question wants you to find the change in momentum.

    Ft = mv - mu

    mv - mu is the change in mometum.

    Ft = change in momentum.

    You know F.

    You know t.


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    #133
    The LeavyC
    Closed Accounts Posts: 50 ✭✭The LeavyC


    Parsley wrote: »
    Went grand for me, probably my best exam. Got exactly 9.81 m/s^2 for g. :D
    Q5 20,000pa for the thumbtack.
    Q7 Resistivity of nichrome - 1.14x10^-6, heat generated by toaster - 120960
    Q8 .01s, .02 Webers and -2v.
    Q11 Change in momentum - 5.4,2.178x10^-19 for the energy of the photon, 1.111x10^-9 for the mass
    Q12a 32.2 for distance, 5.42m for height
    b 423.29 or 211.65 for doppler, depending on how the wording is interpretted.


    was it supposed to be 9.8? i thought i got 8.6 r sumtin.. Gravitys 9.8 on the surface of the earth, but it was asking for 400km above??
    I did get a fair few of the others the same as you tho.

    Did any1 else think that Q5 was harder than usual???


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    #134
    Stevieo
    Closed Accounts Posts: 63 ✭✭Stevieo


    Cokehead Mother wrote: »
    Noooo

    The question wants you to find the change in momentum.

    Ft = mv - mu

    mv - mu is the change in mometum.

    Ft = change in momentum.

    You know F.

    You know t.


    If I couldn't get THAT, I'm feeling I failed miserably elsewhere! Nice one...


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    #135
    michaelkhan3
    Closed Accounts Posts: 11 ✭michaelkhan3


    nyangnyang wrote: »
    I am in shock. I learned 26 of the 28 experiments. The 2 i didnt learn came up.Anyone able to work out the probability of that(im serious i wanna know)

    The probability is 17/63. And I got 14 pions. Over all it was easy, Just a few bits of theory I didnt know. I forgot the 237.15 Kelvin


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    #136
    tabouli
    Registered Users Posts: 163 ✭✭tabouli


    michaelkhan3 wrote: »
    I forgot the 237.15 Kelvin

    I did too. Oh the shame...:o


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    #137
    michaelkhan3
    Closed Accounts Posts: 11 ✭michaelkhan3


    nyangnyang wrote: »
    I am in shock. I learned 26 of the 28 experiments. The 2 i didnt learn came up.Anyone able to work out the probability of that(im serious i wanna know)


    Ya I think I got the exact same. I didnt think I got the 2nd part rigth.


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    #138
    michaelkhan3
    Closed Accounts Posts: 11 ✭michaelkhan3


    alan4cult wrote: »
    No the right answer is 5.418

    Method 1:
    Consider man as a bullet upwards
    u=9.2
    v=0
    a=-9.8

    s= 4.318

    Now that tells you how much he has risen.
    And his centre of gravity is 1.1m above ground so you get 4.318 +1.1 = 5.418

    Methid 2:
    Treat it like energy
    Potential energy at start(taking ground as Pe=0)
    = mgh = 1.1mg
    Kinetic energy at start = 1/2m(9.2)^2 = 42.32m

    Potential Energy at end = mgh
    Ke = 0

    1.1mg + 42.32m = mgh
    1.1g + 42.32 = gh
    1.1 + 4.318 = h (Divide across by g)
    h = 5.418

    Brilliant I thought I had it wrong but I did that exactly


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    #139
    muffinman
    Registered Users Posts: 494 ✭✭muffinman


    Stevieo wrote: »
    put warning stickers on the toaster.

    :D LOL


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    #140
    nyangnyang
    Closed Accounts Posts: 40 ✭nyangnyang


    michaelkhan3 wrote: »
    The probability is 17/63.

    no its not its 1 out of just under 400


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    #141
    The LeavyC
    Closed Accounts Posts: 50 ✭✭The LeavyC


    michaelkhan3 wrote: »
    The probability is 17/63. And I got 14 pions. Over all it was easy, Just a few bits of theory I didnt know. I forgot the 237.15 Kelvin

    Yeah that probability is definitely wrong but i cba to work it out.
    **actually i just tried and i go 6/325? I'm probably wrong.
    And you still don't know the kelvin thing because its actually 273.15, but maybe that was a typo? i didn't do that question anyways.
    Did any1 think they were being tricky in Q3 by having to devide by 2? i nearly didn't realize what they meant was that was 2x the answer.


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    #142
    Decerto
    Registered Users Posts: 309 ✭✭Decerto


    wat is 100C in kelvin ?


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    #143
    Slashman X
    Registered Users Posts: 140 ✭✭Slashman X


    373.15 I think, but don't trust me on that :p


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    #144
    Cokehead Mother
    Closed Accounts Posts: 773 ✭✭✭Cokehead Mother


    Decerto wrote: »
    wat is 100C in kelvin ?

    373.15

    They'll probably accept 373.


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    #145
    The-Rafalution
    Registered Users Posts: 130 ✭✭The-Rafalution


    anyone have the correct answer for latent heat of fusion and for the pendulum i stupidly forgot to divide time by 30 but i squared it and drew l gainst t2...do you think ill loose much for that?


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    #146
    Slashman X
    Registered Users Posts: 140 ✭✭Slashman X


    L.Ht was about 3.1-3.4 x10^5

    For g I got pi^2 ie. 9.8696 :cool:


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    #147
    tabouli
    Registered Users Posts: 163 ✭✭tabouli


    The-Rafalution wrote: »
    anyone have the correct answer for latent heat of fusion and for the pendulum i stupidly forgot to divide time by 30 but i squared it and drew l gainst t2...do you think ill loose much for that?

    I know someone who did that the last time it came up, he got about 20/40.


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    #148
    The Pants Dance
    Closed Accounts Posts: 1 ✭The Pants Dance


    Me thinks i got 3.18x10^5 for the latent heat. And you'll probably lose the initial marks but maybe you wont for the calculations....as long as the formula was used


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    #149
    The-Rafalution
    Registered Users Posts: 130 ✭✭The-Rafalution


    i got 275643.5 for the latent heat.....must be wrong?


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    #150
    muffinman
    Registered Users Posts: 494 ✭✭muffinman


    The LeavyC wrote: »
    Did any1 think they were being tricky in Q3 by having to devide by 2?

    Well I'd say if you hadn't already noticed, the 120degree angle would have made it clear


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    #151
    Ally_ally
    Registered Users Posts: 26 ✭Ally_ally


    nyangnyang wrote: »
    LMAO,1 and 3 were the ones i couldn't do as well and I also tried the graph on q1 and also got it wrong. Great minds and terrible minds think alike!!:D
    haha! fairplay to us!!! i left q.1 to the end of the paper coz i looked at it and had a vague memory of us counting oscillations in class....(which hypnotised me and probable put me to sleep...thats why i couldn't remember the rest!!) my graph was goin backwards...like a thermistor and temperature!!!! hahaha! how wrong is that! i'm so annoyed though...thats me down 10 % anyway and i wanted an a in physics :( i'l prob get a b3 id say


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