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Physics - How'd it go?

124

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  • Closed Accounts Posts: 175 ✭✭Blerdiii


    FreeT wrote: »
    Hey boarders, did anyone get any of these answers?:

    Q1: Mass = 3.51 kg
    Q2: Latent heat = 2,338,477 J/kg
    Q3: n = 1.492
    Q6: a = 1.09 m/s/s
    Height above surface = 3.392x10^8 m
    Velocity = 1022.9 m/s
    Q7: Speed = 1.48x10^6 m/s
    Q11b: 0.2 W/kg
    g: 6.25 cm


    Thanks in advance.
    q1-2.15/2.38 kg
    2,same
    3,almost same
    7-50.847x10^6
    11b-same
    g-same!:)


  • Registered Users Posts: 59 ✭✭FreeT


    jawileth wrote: »
    for Q8(ii) did anybody else use P=RI^2 and change it to P=V/R? i think thats right!

    and for Q10 (ii) did anyone else get 0.725J?

    Q10 (iii)!! as scabby a question as i've ever seen! your dont have to know the make up specific of mesons!!

    Q10ii: My kinetic energy worked out at 3.69x10^(-14) J

    When I got to (iii) I was seriously considering just trying 10B!


    RE: blerdii
    It's really starting to look like i fecked up question 1...


  • Closed Accounts Posts: 175 ✭✭Blerdiii


    FreeT wrote: »
    Q10ii: My kinetic energy worked out at 3.69x10^(-14) J

    When I got to (iii) I was seriously considering just trying 10B!


    RE: blerdii
    It's really starting to look like i fecked up question 1...
    ah sure youll be grand! you can lose 60 marks and still get a1 sure.

    but exact same answer for kinetic energy!*fingers crossed* :)


  • Posts: 0 [Deleted User]


    Blerdiii wrote: »
    ah sure youll be grand! you can lose 60 marks and still get a1 sure.

    but exact same answer for kinetic energy!*fingers crossed* :)
    *40 marks


  • Closed Accounts Posts: 175 ✭✭Blerdiii


    *40 marks
    XD oops was thinking of 360 marks and 60 jumped out XD


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  • Closed Accounts Posts: 2 DogsOnDub


    Conor108 wrote: »
    Anyone get the speed of that star in the Doppler effect question?

    i got 4.6x10^6 m/s
    surprised it worked out, don't know if its right though


  • Users Awaiting Email Confirmation Posts: 114 ✭✭UglyFuc


    couple of questions here

    how was the water cooled below room temperature - i said leave it in the fridge
    i said sensitive thermomerer gives more accurate result

    below 30 degrees = total internal reflection occurs, no emergent ray to measure angle

    what was the conditions of equlibrium?
    what device adjusts the radio tuning? please say diode
    why does a note sound different wih different instruments?
    tell me the direction of the charge P was to the right


  • Registered Users Posts: 1,096 ✭✭✭Occono


    I did 9 questions, I think I did fine on 6 of them but The Doppler Effect, Nuclear and Particle Physics tripped me up. Oh well.


  • Registered Users Posts: 59 ✭✭FreeT


    UglyFuc wrote: »
    couple of questions here

    how was the water cooled below room temperature - i said leave it in the fridge
    i said sensitive thermomerer gives more accurate result

    below 30 degrees = total internal reflection occurs, no emergent ray to measure angle

    what was the conditions of equlibrium?
    what device adjusts the radio tuning? please say diode
    why does a note sound different wih different instruments?
    tell me the direction of the charge P was to the right


    Fridge should be okay.
    Thermometer does give more accurate results
    Nope, total internal reflection occurs when the incident ray is 90 degrees. It's more to do with greater percentage error.

    Equilibrium when: forces up = forces down and net clockwise moments = net anticlockwise moments.

    Sorry, i think it's capacitor

    Different qualities of notes.

    Didn't do that question.


  • Users Awaiting Email Confirmation Posts: 114 ✭✭UglyFuc


    FreeT wrote: »
    Fridge should be okay.
    Thermometer does give more accurate results
    Nope, total internal reflection occurs when the incident ray is 90 degrees. It's more to do with greater percentage error.

    Equilibrium when: forces up = forces down and net clockwise moments = net anticlockwise moments.

    Sorry, i think it's capacitor

    Different qualities of notes.

    Didn't do that question.

    fuc it, i knew the equlibrium and wrote down some stupid ****e.
    got the quality of notes, mentioned overtones.
    i think i said the critical angle aswel, might scrap afew marks..


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  • Closed Accounts Posts: 4 cat42


    Holysock wrote: »
    Does anyone know if saying 'Set up a speaker emmiting a continual frequency and then observing the change while running away from it' will work for the explanation of the Doppler effect?I know it was supposed to be the ripple tank!


    ooo..thats what it was.. i had no idea what it was called..just called it a bath!!..umm not sure about that, you will prob get some marks for it though:p


  • Closed Accounts Posts: 24 karen-xxxxx


    Hardest paper ever :( Looking at these answers depressing me :(


  • Registered Users Posts: 1,096 ✭✭✭Occono


    What is the unit of refractive index?


  • Closed Accounts Posts: 311 ✭✭H2student


    There's no unit? At least that's what I hope.


  • Closed Accounts Posts: 96 ✭✭Indigo Sunrise


    Occono wrote: »
    What is the unit of refractive index?

    It has no unit. It's just a ratio.


  • Closed Accounts Posts: 3,768 ✭✭✭almostnever


    Occono wrote: »
    What is the unit of refractive index?

    Don't think there is one on the course. :)


  • Registered Users Posts: 1,096 ✭✭✭Occono


    Oh good :) Well, except I wasted too much time trying to think of one...Now I'm just annoyed at how much I screwed up 10. A. :(


  • Closed Accounts Posts: 4 jawileth


    FreeT wrote: »
    Hey boarders, did anyone get any of these answers?:

    Q1: Mass = 3.51 kg
    Q2: Latent heat = 2,338,477 J/kg
    Q3: n = 1.492
    Q6: a = 1.09 m/s/s
    Height above surface = 3.392x10^8 m
    Velocity = 1022.9 m/s
    Q7: Speed = 1.48x10^6 m/s
    Q11b: 0.2 W/kg
    g: 6.25 cm

    Thanks! i got Q2 and 3! didnt get any the same in Q6 except for the velocity! gettin worried about that one, i thought i did well in that one but now not sure!
    i didnt get a = 1.09, i got a = 3.something!
    height above = 3.456x10^8

    dont think im gettin an A1 anymore!:D I cant really complain can i


  • Registered Users Posts: 489 ✭✭clartharlear


    MavisDavis wrote: »
    Also, I didn't know data-loggers were a required part of the course. I've always used ticker-tape timers and whatnot instead of them. Question 12 (a) was a bust for me - I've never seen a data-logger let alone used one!
    Data-loggers are recommended, not required, in the syllabus. All state schools would have been given funding to get them, though not everyone uses them. You didn't really need to know much about data loggers for the question, just describe the motion given by the graph.
    did anyone, for 10 (a) (iii) write more than one meson? i think it was just meant to be pion and anti-pion but it's not really clear, so in the exam i wrote pion +, pion -, kaon + and kaon - :S
    positive and negative pions. the syllabus is clear that you are expected to know the specific composition of two baryons, but only says "Mesons composed of any quark and an anti-quark." Did a lot of people take issue with this question? I'll write a letter suggesting it is brought up in the marking scheme conference.
    You were meant to solve q6 using ratios! I think! :pac:
    there is more than one way to skin a cat!
    muffinz wrote: »
    the ripple tank?D: i wrote all about a person swinging an object emitting a continous pitch, and when it came towards us it was higher etc.... 0 marks for me then D:
    that's the one in the book
    Occono wrote: »
    What is the unit of refractive index?
    there is none!


  • Users Awaiting Email Confirmation Posts: 114 ✭✭UglyFuc


    was the variation in risistance around 300 ohms?
    the temp was varied by applying heat ie a bunson burner
    and the risistance was measured with an ohmmeter?


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  • Closed Accounts Posts: 69 ✭✭IronGirl92


    FreeT wrote: »
    Fridge should be okay.
    Thermometer does give more accurate results
    Nope, total internal reflection occurs when the incident ray is 90 degrees. It's more to do with greater percentage error.

    Equilibrium when: forces up = forces down and net clockwise moments = net anticlockwise moments.

    Sorry, i think it's capacitor

    Different qualities of notes.

    Didn't do that question.


    Direction was towards the left. Always from plus to minus. And you place a single positive charge at 'p' to work out the answers.

    And I described adding Ice and stirring until the wanted temperature was reached, fridge should be grand though, they always accept logical answers for them!


  • Closed Accounts Posts: 175 ✭✭Blerdiii


    UglyFuc wrote: »
    couple of questions here

    how was the water cooled below room temperature - i said leave it in the fridge
    i said sensitive thermomerer gives more accurate result

    below 30 degrees = total internal reflection occurs, no emergent ray to measure angle

    what was the conditions of equlibrium?
    what device adjusts the radio tuning? please say diode
    why does a note sound different wih different instruments?
    tell me the direction of the charge P was to the right

    hmm say your ok because there is no " wrong " way to cool water, i just had it in a beaker of ice :)


  • Closed Accounts Posts: 3 eoin123


    i got the direction for the doppler correct but used wrong formula anyone know how many marks dat will lose me


  • Registered Users Posts: 3,739 ✭✭✭johnmcdnl


    UglyFuc wrote: »
    was the variation in risistance around 300 ohms?
    the temp was varied by applying heat ie a bunson burner
    and the risistance was measured with an ohmmeter?

    it was per unit kelvin so you had to divide it by 10 to get 2.5 ohms in my case per degree Celsius.. i think.. i forgot to do that part though :( and i think you may have had to do something with the -273.15 to change for Kelvins but don't quote me on that...

    most of the marks are for the graph and getting the 250-300 ohms ish ish variation.. shouldn't loose too much for forgetting the last bit


  • Registered Users Posts: 50 ✭✭Leavenotrace


    For question 6

    The bit without G i assumed they didnt want you to use it

    So this is what i did

    F directly proportional to 1/(d)squared

    F=k/d(squared)
    mg=k/d(squared)
    9.81m=k/(4.04496x10^13)
    k=(m)3.96810576x10^14
    so i now know k

    ma=k/d(squared)
    ma=k/3.640464x10^14
    ma=(m)(3.96810576x10^14)/3.640464x10^14
    m's cancel
    a=(3.96810576x10^14)/3.640464x10^14
    a=1.09m/s/s


  • Registered Users Posts: 233 ✭✭KealanOCarroll


    Blerdiii wrote: »
    hmm say your ok because there is no " wrong " way to cool water, i just had it in a beaker of ice :)

    Adding ice is the wrong way:P The way you find the mass of the ice is subtract the initial mass of the apparatus from the final mass i.e. the ice+water+calorimeter minus water+calorimeter = ice.
    The way to find the mass of the steam is the same: steam+water+calorimeter minus h20+calorim = steam.

    If you add ice to cool, then put steam in it, how do you know at the end where the extra mass came from? you can find out that say 100g of ice and steam were added, but how much of that 100g was ice and how much was steam?

    You could probably argue that youd add the ice, wait for it to melt, then weigh the lot, THEN add the steam....but a fridge is easier!


    q6 ya didnt need G or M....f = GM over D^2....for the guys to be weightless the gravitational force of the earth = gravitational force of the moon. so G(81)M / d^2 = GM / D^2....G and M cancel...end up with 9d = D...your given the dist between the centres...solve from there its jus algebra:)


    The Q8 (i think?) one with the hairdryer....it said "the fan develops a fault"....how are we supposed to know whether the fault was a short, an open circuit, or the fan jamming? They all have different results but could all be read as "fault"


  • Registered Users Posts: 233 ✭✭KealanOCarroll


    johnmcdnl wrote: »
    it was per unit kelvin so you had to divide it by 10 to get 2.5 ohms in my case per degree Celsius.. i think.. i forgot to do that part though :( and i think you may have had to do something with the -273.15 to change for Kelvins but don't quote me on that...

    most of the marks are for the graph and getting the 250-300 ohms ish ish variation.. shouldn't loose too much for forgetting the last bit

    The variation in R was 300...the change in temperature was 10 degrees, given in the question. Thus the change in R per 1 degree was 30 ohms....

    The Kelvin anad the Celcius are the same scale so theres no subtracting 273....they start at different places but a change in 10K is the exact same as a change in 1C....


  • Registered Users Posts: 3,739 ✭✭✭johnmcdnl


    The variation in R was 300...the change in temperature was 10 degrees, given in the question. Thus the change in R per 1 degree was 30 ohms....

    The Kelvin anad the Celcius are the same scale so theres no subtracting 273....they start at different places but a change in 10K is the exact same as a change in 1C....


    yeah kelvins are the same divisions as Celsius so the answer is 30ohms.. gonna shoot myself now for forgetting to divide by 10... :mad::mad::rolleyes:


  • Closed Accounts Posts: 6 Mad Scone


    A1 in the bag!!!!:D Wish I could say the same for Accounting!:mad:


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  • Closed Accounts Posts: 3 dmp07


    For question 6

    The bit without G i assumed they didnt want you to use it

    So this is what i did

    F directly proportional to 1/(d)squared

    F=k/d(squared)
    mg=k/d(squared)
    9.81m=k/(4.04496x10^13)
    k=(m)3.96810576x10^14
    so i now know k

    ma=k/d(squared)
    ma=k/3.640464x10^14
    ma=(m)(3.96810576x10^14)/3.640464x10^14
    m's cancel
    a=(3.96810576x10^14)/3.640464x10^14
    a=1.09m/s/s

    i got the same answer by using ratio
    g= 9.8 when R= earth's radius
    g= 9.8/4 when R= twice the earth's radius
    g = 9.8/9 when R= three times the earth's radius

    9.8/9=1.08888888889


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