Advertisement
If you have a new account but are having problems posting or verifying your account, please email us on hello@boards.ie for help. Thanks :)
Hello all! Please ensure that you are posting a new thread or question in the appropriate forum. The Feedback forum is overwhelmed with questions that are having to be moved elsewhere. If you need help to verify your account contact hello@boards.ie

** HL Physics Before / after **

1…34689…19

Comments

  • #152
    CrashBandicoot Girl
    Registered Users Posts: 101 ✭✭CrashBandicoot Girl


    Hey does anyone have a list of formulae and figures that you need but arent in the table?? Thanks :)


  • #153
    dorcan
    Registered Users Posts: 19 ✭dorcan


    http://https://www.youtube.com/watch?v=U0kXkWXSXRA

    partical physics in a nut shell lads


  • #154
    Monsieur Folie
    Registered Users, Registered Users 2 Posts: 1,988 ✭✭✭Monsieur Folie


    dorcan wrote: »
    http://https://www.youtube.com/watch?v=U0kXkWXSXRA

    partical physics in a nut shell lads

    I love that song! :D
    Hank Green is some man for the science..


  • #155
    Chikablam
    Registered Users, Registered Users 2 Posts: 161 ✭✭Chikablam


    Raeral wrote: »
    Nah I'm pretty sure 1m is required no matter what distance you are from the mirror, so long as the top of the mirror is level with the top of your head. If you look at this image here, you see how, when the person looks halfway down the mirror ie 1m they see there feet as i=r: http://www.google.ie/search?newwindow=1&safe=off&q=length%20of%20mirror%20for%202m%20person&um=1&ie=UTF-8&hl=en&tbm=isch&source=og&sa=N&tab=wi&ei=u928UdGKFo2g7AbDw4GwDg&biw=768&bih=928&sei=wt28UZeCGYXb7Aa3joCwAQ#biv=i%7C1%3Bd%7C9XONDC6G1cOCOM%3A

    Yes, but say if you're standing 50 away, your image will be tiny, and so an even smaller mirror will be needed.
    Obviously this is not a realistic example, but it still remains that the further away you stand, the smaller the mirror needed, making the question flawed.


  • #156
    Tweej
    Registered Users, Registered Users 2 Posts: 171 ✭✭Tweej


    Chikablam wrote: »
    Yes, but say if you're standing 50 away, your image will be tiny, and so an even smaller mirror will be needed.
    Obviously this is not a realistic example, but it still remains that the further away you stand, the smaller the mirror needed, making the question flawed.

    Untrue. Try drawing a diagram, using the laws of reflection, and you'll see it always needs to be height/2


  • Advertisement
  • #157
    Tweej
    Registered Users, Registered Users 2 Posts: 171 ✭✭Tweej


    Note; people, one thing to remember, spend an hour before the exam, simply looking at what you have in your formula tables if you don't already know. It is a gold mine for definitions, formulas, etc etc. This sounds obvious, but it helps tremendously


  • #158
    Leaving Cert Student
    Registered Users, Registered Users 2 Posts: 1,026 ✭✭✭Leaving Cert Student


    Chikablam wrote: »
    Yes, but say if you're standing 50 away, your image will be tiny, and so an even smaller mirror will be needed.
    Obviously this is not a realistic example, but it still remains that the further away you stand, the smaller the mirror needed, making the question flawed.

    no this isn't correct because the angle of reflection is also getting smaller as you step farther back. So it will always be the case that to see your toes, the point of incidence/reflection is half your height - 1m


  • #159
    Leaving Cert Student
    Registered Users, Registered Users 2 Posts: 1,026 ✭✭✭Leaving Cert Student


    Does anyone have a list of names we need to know?
    Dirac found anti-matter, right?
    Stoney named electron?
    Milikan found the value of the electron?
    Pauli proposed neutrino...
    Cockroft and Walton did the gold foil experiment to find the structure of the atom..

    Anyone else I am leaing out? Would hate to lose marks on something like this


  • #160
    Brendan1234
    Registered Users Posts: 32 ✭Brendan1234


    Leaving Cert Student wrote: »
    Does anyone have a list of names we need to know?
    Dirac found anti-matter, right?
    Stoney named electron?
    Milikan found the value of the electron?
    Pauli proposed neutrino...
    Cockroft and Walton did the gold foil experiment to find the structure of the atom..

    Anyone else I am leaing out? Would hate to lose marks on something like this

    Dirac only predicted the existence of anti matter as far as I know, although you'd probably get the marks for saying he discovered it. Rutherford did the gold foil experiment, Cockcroft and Walton split the atom for the first time.
    Apart from those, one year they asked who discovered the x-ray (Wilhelm Röntgen), cowen and reines confirmed the existence of the neutrino, that Anderson guy, can't remember his full name, that discovered the positron. I don't think they've ever asked for a scientist outside of the modern physics section, but I think it's good to know that Henry Cavendish first measured the gravitational constant. I'm probably forgetting someone but they're all that come to mind.


  • #161
    Raeral
    Registered Users Posts: 97 ✭✭Raeral


    Leaving Cert Student wrote: »
    Does anyone have a list of names we need to know?
    Dirac found anti-matter, right?
    Stoney named electron?
    Milikan found the value of the electron?
    Pauli proposed neutrino...
    Cockroft and Walton did the gold foil experiment to find the structure of the atom..

    Anyone else I am leaing out? Would hate to lose marks on something like this

    They also asked who came up with the name quark one year (James Joyce). But as Brendan said above it doesn't tend to come up that often.


  • Advertisement
  • #162
    Leaving Cert Student
    Registered Users, Registered Users 2 Posts: 1,026 ✭✭✭Leaving Cert Student


    Sound boys!


  • #163
    jmillz
    Registered Users Posts: 26 ✭jmillz


    I'm just hoping on a full question on magnetism, I already have the four others picked so hopefully!


  • #164
    xJEx
    Registered Users Posts: 166 ✭✭xJEx


    Raeral wrote: »
    They also asked who came up with the name quark one year (James Joyce). But as Brendan said above it doesn't tend to come up that often.

    Gell-Mann named it actually, he just took it from Joyce's book. Joyce was no more than a writer, just saying :P


  • #165
    Leaving Cert Student
    Registered Users, Registered Users 2 Posts: 1,026 ✭✭✭Leaving Cert Student


    xJEx wrote: »
    Gell-Mann named it actually, he just took it from Joyce's book. Joyce was no more than a writer, just saying :P

    the marking scheme gave joyce tbf.

    So no other phamous physicists to be learnt off??


  • #166
    xJEx
    Registered Users Posts: 166 ✭✭xJEx


    Leaving Cert Student wrote: »
    the marking scheme gave joyce tbf.

    So no other phamous physicists to be learnt off??

    Ah alright. Need to know Becquerel and the Curries. And I think Callan has come up about the induction coil?


  • #167
    Leaving Cert Student
    Registered Users, Registered Users 2 Posts: 1,026 ✭✭✭Leaving Cert Student


    xJEx wrote: »
    Ah alright. Need to know Becquerel and the Curries. And I think Callan has come up about the induction coil?

    Is that applied electricity?

    If anyone can think of any other physicists please let me know!


  • #168
    Leaving Cert Student
    Registered Users, Registered Users 2 Posts: 1,026 ✭✭✭Leaving Cert Student


    Given that the masses of the uranium, caesium and rubidium nuclei are 235.0439u,
    140.9196u and 92.9217u respectively and the mass of the neutron is 1.0087u,
    calculate, in joules, the energy given off on the right-hand side of the equation. (13)
    ( e = 1.6��10–19 C, C = 3��108 m s–1, 1u = 1.66��10–27 kg )

    The equation is basically uranium and a neutron on the left hand side go to.... caesium, rubidium and 2 neutrons on the right hand side.
    Calculate the energy given off due to the mass defect? I get an answer but it's not quite what the marking scheme are getting? Does anyone wanna try this and see what you get?


  • #169
    MarieCurie22
    Registered Users Posts: 204 ✭✭MarieCurie22


    xJEx wrote: »
    Ah alright. Need to know Becquerel and the Curries. And I think Callan has come up about the induction coil?

    You need to Know Dirac (Antiparticles) hes been asked several times


  • #170
    D_s
    Registered Users Posts: 149 ✭✭D_s


    Leaving Cert Student wrote: »
    Does anyone wanna try this and see what you get?

    I'm getting 2.898 x -11 joules, or 180.87MeV

    What's in the marking scheme?


  • #171
    MarieCurie22
    Registered Users Posts: 204 ✭✭MarieCurie22


    Anybody else having nightmares about this exam?


  • Advertisement
  • #172
    xJEx
    Registered Users Posts: 166 ✭✭xJEx


    D_s wrote: »
    I'm getting 2.898 x -11 joules, or 180.87MeV

    What's in the marking scheme?

    Same.
    What question is it?


  • #173
    D_s
    Registered Users Posts: 149 ✭✭D_s


    xJEx wrote: »
    Same.
    What question is it?

    C'mon LCStudent, don't leave us hanging!


  • #174
    Leaving Cert Student
    Registered Users, Registered Users 2 Posts: 1,026 ✭✭✭Leaving Cert Student


    Sorry boys, I got the same. marking scheme says it is half that. The formula they used at the end was half of mc^2 and not just mc^2

    Think they made a mistake?


  • #175
    decisions
    Closed Accounts Posts: 8,207 ✭✭✭decisions


    Are they looking for the energy to get one nutrino?


  • #176
    Leaving Cert Student
    Registered Users, Registered Users 2 Posts: 1,026 ✭✭✭Leaving Cert Student


    decisions wrote: »
    Are they looking for the energy to get one nutrino?

    No the question asked for the energy?


  • #177
    D_s
    Registered Users Posts: 149 ✭✭D_s


    Leaving Cert Student wrote: »
    No the question asked for the energy?

    I assume this is a mock and not a past paper?


  • #178
    Leaving Cert Student
    Registered Users, Registered Users 2 Posts: 1,026 ✭✭✭Leaving Cert Student


    D_s wrote: »
    I assume this is a mock and not a past paper?

    Yep


  • #179
    Leaving Cert Student
    Registered Users, Registered Users 2 Posts: 1,026 ✭✭✭Leaving Cert Student


    I'd say they made a mistake. Just wanted to be sure this .5mc^2 formula didn't mean something else!


  • #180
    maxim
    Registered Users Posts: 112 ✭✭maxim


    CrashBandicoot Girl - did you ever get a reply to your question - "
    Hey does anyone have a list of formulae and figures that you need but arent in the log tables?? Thanks "
    and if so, what were they!!!!
    Panicking here and don't have an hour to waste going thro!! Please help!


  • Advertisement
  • #181
    Leaving Cert Student
    Registered Users, Registered Users 2 Posts: 1,026 ✭✭✭Leaving Cert Student


    maxim wrote: »
    CrashBandicoot Girl - did you ever get a reply to your question - "
    Hey does anyone have a list of formulae and figures that you need but arent in the log tables?? Thanks "
    and if so, what were they!!!!
    Panicking here and don't have an hour to waste going thro!! Please help!

    I am afraid I don't but would be interested if anyone has one.

    Also list of derivations on course, non mandatory experiments that might come up etc.?


Advertisement