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*** Leaving Cert PHYSICS 2014 ***

123578

Comments

  • #202
    Lara_15
    Registered Users Posts: 704 ✭✭✭Lara_15


    deadpixel wrote: »
    Can a graph be asked for the speed of sound in air question? Its in my text book but not listed in the exam paper graph breakdown so I'm not sure. Doesn't seem too complicated anyway just checking.

    I was thinking the same earlier. Its in my book too but not in my reviswise
    I just thought because the revisewise is so ****e they might have forgotten it but maybe not


  • #203
    aleatorio
    Registered Users, Registered Users 2 Posts: 1,673 ✭✭✭aleatorio


    For the measurement of specific heat capacity do we need to know how to do it the electrical way as well as the mechanical way or??


  • #204
    Teachm
    Registered Users Posts: 45 ✭Teachm


    aleatorio wrote: »
    For the measurement of specific heat capacity do we need to know how to do it the electrical way as well as the mechanical way or??

    Both can come up .mechanical 2007 q2.
    Energy lost by hot copper =energy gained by water +energy gained by calorimeter
    390x.032x78.5=cx.0455x4.5 + 390x.0557x4.5
    979.68=.20475c + 97.7535
    979.68 - 97.735 = 0.20475c
    881.945
    0.20475
    4307.42 J/kg/K
    Must write unit other way


    If its a joule meter your left hand side of equation will just have a value eg.2345J


  • #205
    EoghanIRL
    Registered Users, Registered Users 2 Posts: 4,080 ✭✭✭EoghanIRL


    aleatorio wrote: »
    For the measurement of specific heat capacity do we need to know how to do it the electrical way as well as the mechanical way or??

    Yes you need to know both . They don't have to give you an option . It's basically the same anyway just different energy source .


  • #206
    aleatorio
    Registered Users, Registered Users 2 Posts: 1,673 ✭✭✭aleatorio


    EoghanIRL wrote: »
    Yes you need to know both . They don't have to give you an option . It's basically the same anyway just different energy source .

    Ok, cos the one we learned was the mechanical one, so Ill just learn the electrical too just in case :o


  • #207
    Daithi MacG
    Registered Users Posts: 113 ✭✭Daithi MacG


    Aspiring wrote: »
    The derivation of the diffraction grating formula hasn't come up in a while. Dunno if they'd put it on tho since it's probably the hardest (imo) derivation on the syllabus.

    I think it's probably the easiest :o I think when I draw the diagram it suits me...Getting that Kepler's Law is the hardest for me...I don't know what's going on when I try to do it, I just plug everything in everywhere.


  • #208
    RP77
    Registered Users Posts: 14 ✭RP77


    deadpixel wrote: »
    Can a graph be asked for the speed of sound in air question? Its in my text book but not listed in the exam paper graph breakdown so I'm not sure. Doesn't seem too complicated anyway just checking.

    Yes there is a chance that the graph could come up for this question. It appeared on one of the mock papers a few years back. Length on y axis versus 1/freq on x axis. The slope gives c, the speed of sound. The y intercept gives a value for -0.3d where d is the internal diameter of the resonance tube. 0.3d is the end correction ( the location of the antinode).


  • #209
    Teachm
    Registered Users Posts: 45 ✭Teachm


    RP77 wrote: »
    Yes there is a chance that the graph could come up for this question. It appeared on one of the mock papers a few years back. Length on y axis versus 1/freq on x axis. The slope gives c, the speed of sound. The y intercept gives a value for -0.3d where d is the internal diameter of the resonance tube. 0.3d is the end correction ( the location of the antinode).

    Is it not lambda on y axis?


  • #210
    plmko
    Registered Users Posts: 160 ✭✭plmko


    Teachm wrote: »
    Is it not lambda on y axis?

    Yeah you're correct


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  • #211
    deadpixel
    Registered Users Posts: 20 ✭deadpixel


    Real world physics has l in metres on y-axis vs 1/f (f/hz) Straight line, not through the origin as y-intercept is -.3d as stated above. Slope would be c/4 though from the formula c =4f(l+.3d)
    I'd say we're more to just be asked to figure it p
    out from the formula if the experiment does come up but good to know just in case.


  • #212
    LoveLamps
    Registered Users Posts: 781 ✭✭✭LoveLamps


    What derivations should i learn?


  • #213
    Teachm
    Registered Users Posts: 45 ✭Teachm


    deadpixel wrote: »
    Real world physics has l in metres on y-axis vs 1/f (f/hz) Straight line, not through the origin as y-intercept is -.3d as stated above. Slope would be c/4 though from the formula c =4f(l+.3d)
    I'd say we're more to just be asked to figure it p
    out from the formula if the experiment does come up but good to know just in case.



    This is correct.l on y axis versus 1 over f and slope x4 = c
    Plmko also correct if lambda on y axis versus 1 over f then slope = c

    Did see it on a mock but think it a bit nasty if it came up however deadpixel is right to say better safe than sorry.


  • #214
    otpmb
    Registered Users Posts: 84 ✭✭otpmb


    Daithi MacG wrote: »
    ...Getting that Kepler's Law is the hardest for me...I don't know what's going on when I try to do it, I just plug everything in everywhere.

    What is Kepler's Law?


  • #215
    Teachm
    Registered Users Posts: 45 ✭Teachm


    LoveLamps wrote: »
    What derivations should i learn?

    Equations of motion
    nlambda=dSin theta
    F=qvB (electromag)
    Resistors in series and parallel

    The rest are in SHM and circular motion for the applied Maths students or those who love mechanics


  • #216
    flump_master
    Closed Accounts Posts: 89 ✭✭flump_master


    otpmb wrote: »
    What is Kepler's Law?

    It's T^2= [4(pi^2)(r^3)]/GM

    You get it by equating centripetal force and gravity and letting w^2= 4(pi^2)/T^2


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  • #217
    Days 298
    Closed Accounts Posts: 1,311 ✭✭✭Days 298


    Ive ignored Kepler and angular velocity. I know it but havent recently gone over it. Dont think itll come up tomorrow as it a question on planets came up last year IIRC. Either Hooke or SHM.


  • #218
    forlifebaby
    Registered Users Posts: 31 ✭forlifebaby


    Lara_15 wrote: »
    I thought physics was first, then accounting

    Oh holy mother of God. Is it??


  • #219
    Teachm
    Registered Users Posts: 45 ✭Teachm


    forlifebaby wrote: »
    Oh holy mother of God. Is it??

    Physics in morning


  • #220
    forlifebaby
    Registered Users Posts: 31 ✭forlifebaby


    Isitthough? wrote: »
    Lol your fine for accounting then, do you know ratios? Im fine with everything but Im a bit dodgey on cash flows for some reason:( I dont know ratios and dont know whether I should do them I did them before but a long time ago...
    Oh and as Lara said Physics is 1st then accounting :p

    I don't know my theory and that's the sad bit..now that I know we have accounting second I will just learn it during the break.

    I am not doing ratio. I know the formula and all. But I only ever get max 85/100 in it. So I am better off knowing the rest. If you know the other 100 markers you should be okay. :) Is published likely to come up this year? It has come up twice in a row before. -.- I just realised that I haven't learned the notes bit on it.

    Ugh.


  • #221
    Isitthough?
    Registered Users, Registered Users 2 Posts: 192 ✭✭Isitthough?


    forlifebaby wrote: »
    I don't know my theory and that's the sad bit..now that I know we have accounting second I will just learn it during the break.

    I am not doing ratio. I know the formula and all. But I only ever get max 85/100 in it. So I am better off knowing the rest. If you know the other 100 markers you should be okay. :) Is published likely to come up this year? It has come up twice in a row before. -.- I just realised that I haven't learned the notes bit on it.

    Ugh.
    It never came up twice in a row cheaking from 1997...You almost gave me a heartattack :....I didn't get time to do the ratio's shame really Im actually good at accounting I just didn't plan well..Hopefully all the good stuff will come up and I Dont know theory either but some of it is fine and you get attempt marks for common sense Ill just read through some tomorrow.


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  • #222
    kn2k10
    Registered Users, Registered Users 2 Posts: 119 ✭✭kn2k10


    Well.. I'm ready to fail this **** exam.


  • #223
    Isitthough?
    Registered Users, Registered Users 2 Posts: 192 ✭✭Isitthough?


    kn2k10 wrote: »
    Well.. I'm ready to fail this **** exam.

    Im actually ****ing bricks at this stage Im so scared Ill fail and if I fail this Ill most likely have to repeat:( I really hope its a nice exam


  • #224
    Aspiring
    Registered Users, Registered Users 2 Posts: 2,204 ✭✭✭Aspiring


    Lads, what's the point worrying and saying how badly you're going to do on here, go cram.


  • #225
    kn2k10
    Registered Users, Registered Users 2 Posts: 119 ✭✭kn2k10


    Aspiring wrote: »
    Lads, what's the point worrying and saying how badly you're going to do on here, go cram.

    I haven't been able to 'cram' for the last two years. Physics makes no sense to me. I was falsely lead to believe that it was a fun practical subject, not another maths subject.
    **** teacher doesn't help either, he didn't even finish the course, but I won't rant.


  • #226
    Aspiring
    Registered Users, Registered Users 2 Posts: 2,204 ✭✭✭Aspiring


    kn2k10 wrote: »
    I haven't been able to 'cram' for the last two years. Physics makes no sense to me. I was falsely lead to believe that it was a fun practical subject, not another maths subject.
    **** teacher doesn't help either, he didn't even finish the course, but I won't rant.

    The whole course material and syllabus are available online. In much more detail than any textbook or teacher will ever have.


  • #227
    Isitthough?
    Registered Users, Registered Users 2 Posts: 192 ✭✭Isitthough?


    Aspiring wrote: »
    Lads, what's the point worrying and saying how badly you're going to do on here, go cram.

    Cramming atm Ill do it till 12 then going to bed Studying till 4 am wont work for me:p


  • #228
    kn2k10
    Registered Users, Registered Users 2 Posts: 119 ✭✭kn2k10


    Stupid question, can you pass using the log tables? Lol

    Also it's a bit late for any new course material now, sorta wish I knew that earlier.


  • #229
    AtomicKoala
    Registered Users, Registered Users 2 Posts: 881 ✭✭✭AtomicKoala


    aleatorio wrote: »
    Ok, cos the one we learned was the mechanical one, so Ill just learn the electrical too just in case :o

    The mechanical one? :eek: What's that? Is it using hot copper or something? :confused:


  • #230
    aleatorio
    Registered Users, Registered Users 2 Posts: 1,673 ✭✭✭aleatorio


    AtomicKoala wrote: »
    The mechanical one? :eek: What's that? Is it using hot copper or something? :confused:

    Yeah you heat a lump of metal up in a water bath :P


  • #231
    AtomicKoala
    Registered Users, Registered Users 2 Posts: 881 ✭✭✭AtomicKoala


    aleatorio wrote: »
    Yeah you heat a lump of metal up in a water bath :P

    What are we, Archimedes? :pac:


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  • #232
    Lara_15
    Registered Users Posts: 704 ✭✭✭Lara_15


    AtomicKoala wrote: »
    The mechanical one? :eek: What's that? Is it using hot copper or something? :confused:
    yes please share your knowledge, I only know the joulemeter one


  • #233
    sirwhy
    Registered Users Posts: 16 ✭sirwhy


    I finished up study there. Get a good sleep in and do some in the morning before the exam. I've found study in the morning to be most helpful


  • #234
    ave123
    Registered Users Posts: 91 ✭✭ave123


    anyone have any final experiment/derivation predictions before tomorrow?


  • #235
    Janeh9
    Registered Users Posts: 111 ✭✭Janeh9


    I've been doing pass since March but I'm pretty certain there is no difference so I'm taking the honours paper tomoro :P


  • #236
    Teachm
    Registered Users Posts: 45 ✭Teachm


    Last min advice.
    Go in and do section a first.dont look at section b till your 3 exp q are done
    CHOOSE YOUR Questionscarefully
    If you are using a formula for a definition,explain what each letter means.
    Make sure you answer every part of q

    Use every min of three hours

    Good luck again


  • #237
    aleatorio
    Registered Users, Registered Users 2 Posts: 1,673 ✭✭✭aleatorio


    G by freefall, latent heat of vaporisation/fusion, snells law/speed of sound/wavelength of light/sonometer and Joules law/Resisitivity
    Induction, SHM, Nuclear reactions, Pair production/annihilation and a nice Q5

    Hopefully I'll get some of this :o


  • #238
    Cakes.
    Registered Users Posts: 2,152 ✭✭✭Cakes.


    Ah gad I'm doomed! Know nothing!


  • #239
    Daniel2590
    Registered Users Posts: 1,645 ✭✭✭Daniel2590


    What a beautiful paper <3 fairly confident for an A1 :D


  • #240
    qweerty
    Closed Accounts Posts: 367 ✭✭qweerty


    Daniel2590 wrote: »
    What a beautiful paper <3 fairly confident for an A1 :D

    I got an A1, but I remember coming on here afterwards and having people like you depress me like hell! :D Glad it went well fo you. Were there any interesting Qs? Joule's Law? What did Q6 involve?


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  • #241
    Daniel2590
    Registered Users Posts: 1,645 ✭✭✭Daniel2590


    Joules law, conservation of momentum, speed of sound in air and snells law were the experiments. Q6 had derivation of F=ma, difference between vectors and scalars, then the calculation was based on a golf ball being hit (find initial speed and Max height)


  • #242
    aleatorio
    Registered Users, Registered Users 2 Posts: 1,673 ✭✭✭aleatorio


    Beautiful paper :D confident for the A1 I think :pac:
    Did every question except for Q6 because ew mechanics.. XD


  • #243
    qweerty
    Closed Accounts Posts: 367 ✭✭qweerty


    Daniel2590 wrote: »
    Joules law, conservation of momentum, speed of sound in air and snells law were the experiments. Q6 had derivation of F=ma, difference between vectors and scalars, then the calculation was based on a golf ball being hit (find initial speed and Max height)

    Thanks for a thorougly comprehensive reply, man.


  • #244
    omara95
    Registered Users Posts: 50 ✭✭omara95


    Nice enough paper. Happy with it.


  • #245
    deadpixel
    Registered Users Posts: 20 ✭deadpixel


    Lovely paper, couldn't have asked for much better in terms of what came up!


  • #246
    aleatorio
    Registered Users, Registered Users 2 Posts: 1,673 ✭✭✭aleatorio


    Ok so I scribbled down a majority of my calculations answers:

    Q2: n=1.175
    Q3: v= 339
    Q4: Temp = 25.5
    Q5: (b) 6.563 x 10^23 (d) 75.6J (h) 2.1627 x 10^-19
    Q7: Energy of photon = 2.8036 x 10^-19 Number of lines = 400
    Q8: 7.628 x 10^24 nuclei
    Q9: Charge = 3.6 x 10^-5C Energy = 2.16 x 10^-4 New capacitance: 4 x 10^-6F
    Q10: speed = 29.025 Resistance = 17.36 ohms
    Q11: Frequency = 2.4177 x 10^14Hz Decay constant = 5.77622 x 10^-4
    Q12:
    (A) Length = 4.13cm Period = 0.2565s
    (C) Mass = 0.014375kg Temp = 21.45 (these are wrong, just realized I only did it for 1 ice cube :()


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  • #247
    Daniel2590
    Registered Users Posts: 1,645 ✭✭✭Daniel2590


    Did anyone who does applied maths use projectiles for Q6 actually? I used max height when Vy = 0 and all that craic :pac:


  • #248
    LifeasaPigeon
    Registered Users, Registered Users 2 Posts: 16 ✭LifeasaPigeon


    Daniel2590 wrote: »
    Did anyone who does applied maths use projectiles for Q6 actually? I used max height when Vy = 0 and all that craic :pac:

    Yeah, and I usually avoid mechanics but it was too lovely not to do :p applied maths finally came in handy for something! :D


  • #249
    qweerty
    Closed Accounts Posts: 367 ✭✭qweerty


    Daniel2590 wrote: »
    Did anyone who does applied maths use projectiles for Q6 actually? I used max height when Vy = 0 and all that craic :pac:

    Lol. I'd say the corrector will think you're such a prat. They'll be dying to deduct marks!


  • #250
    qweerty
    Closed Accounts Posts: 367 ✭✭qweerty


    LifeasaPigeon wrote: »
    Yeah, and I usually avoid mechanics but it was too lovely not to do :p applied maths finally came in handy for something! :D

    Why do you avoid Mechanics considering you do AM?


  • #251
    LifeasaPigeon
    Registered Users, Registered Users 2 Posts: 16 ✭LifeasaPigeon


    qweerty wrote: »
    Why do you avoid Mechanics considering you do AM?

    I'm really bad at it :p doesn't look like I'll be counting it for points :(


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