*** Leaving Cert PHYSICS 2014 ***

Daithi MacG

Nicke011 wrote: »

Lovely paper, it went unexpectedly good
Expecting a high B

The marking scheme is probably going to be very hard,

Q2 1.47
Q5 U-value, go construction studies!
Q6 12. something (about 13 as far as I remember); Let's go applied maths!
Q8 Engineering all the way!
238/92U + 1/0n = 239/95Pu + 2*(0/-1e)
Q12
b) V=-4.28cm
c) T=15.68 degrees

Q.5 I do construction too, but wasn't 100% sure of it :P was it U-value x area x temp difference?
Q.6 I got 13.something I think
Q.12 I got V=-6 exactly 6 though so maybe I'm wrong. And for the Temperature...or the "Temperture" as was the correction...I got 16.something

Anyway, the method is where it's all happening :cool:

aleatorio

Daithi MacG wrote: »

Q.2 was the refractive index I thought? That's Q.4 you're thinking of, is it? For that I added the initial temperature, because my graph was I^2 against change in temp.

No I mean in Q12 with the icecubes :P

Daithi MacG

aleatorio wrote: »

No I mean in Q12 with the icecubes :P

Oh right, now I getcha! But it didn't ask for the change in temperature, it asked for the minimum temperature, so it's all good :cool:

Nicke011

Daithi MacG wrote: »

Q.5 I do construction too, but wasn't 100% sure of it :P was it U-value x area x temp difference?
Q.6 I got 13.something I think
Q.12 I got V=-6 exactly 6 though so maybe I'm wrong. And for the Temperature...or the "Temperture" as was the correction...I got 16.something

Anyway, the method is where it's all happening :cool:

Yeah, for Q5 it's 75.6... (2.8*3*9)
Q6 it's 12 or 13 I can't remember exactly
For Q12 I wrote down -4.28cm so it's either me or you someones wrong

Daithi MacG

Nicke011 wrote: »

Yeah, for Q5 it's 75.6... (2.8*3*9)
Q6 it's 12 or 13 I can't remember exactly
For Q12 I wrote down -4.28cm so it's either me or you someones wrong

For Q12, did you say that F=5, U=30 and use: 1/u - 1/v = 1/f ?

Nicke011

Daithi MacG wrote: »

For Q12, did you say that F=5, U=30 and use: 1/u - 1/v = 1/f ?

Yeah d=20, so r=10, so f=5
U=30

And because its convex both v and f are negative (use 1/-5 for 1/f), and you'll get negative v

Daithi MacG

Nicke011 wrote: »

Yeah d=20, so r=10, so f=5
U=30

And because its convex both v and f are negative (use 1/-5 for 1/f), and you'll get negative v

shiiiiiiiiiiiiiiiii-

jimbob95

how did people go about answering the last part of q2?

Daithi MacG

jimbob95 wrote: »

how did people go about answering the last part of q2?

I said if there is an error in the data, the line of best fit won't be affected as much as the average value. Didn't know what else to say, think I scribbled something down at the end but it's all just a blur...just hoping I get some marks for that anyway.

aleatorio

Daithi MacG wrote: »

I said if there is an error in the data, the line of best fit won't be affected as much as the average value. Didn't know what else to say, think I scribbled something down at the end but it's all just a blur...just hoping I get some marks for that anyway.

Yeah I said that too :pac:

marno21

For q5, the way it said an hour, did you not have to multiply your U value by 3600?

FatRat

Q1, two forces that need watching out for? I said friction and gravity. As in to solve friction, clean the air track and to solve gravity.. Keep it exactly level?

Q3, speed was like 389? And the last part she took the difference in length between both resonances and she had half a wavelength then. And use the formula to find the speed with the wavelength?

Q7, sensors were located in the retina, right?

Q10, speed of ambulance was 1.1 ms??

XtotheZ

marno21 wrote: »

For q5, the way it said an hour, did you not have to multiply your U value by 3600?

thats what I did anyway, god knows if its right

jimbob95

for gravity you adjust the slope until the trolley is moving with a constant velocity. the retina is right as far as i know while speed of the ambulance was roughly 29 ms.. didnt do Q3!

Daithi MacG

marno21 wrote: »

For q5, the way it said an hour, did you not have to multiply your U value by 3600?

Yeah I said 76.5J/s so multiplied it by 60 twice to get per J/hour

FatRat wrote: »

Q1, two forces that need watching out for? I said friction and gravity. As in to solve friction, clean the air track and to solve gravity.. Keep it exactly level?

Q3, speed was like 389? And the last part she took the difference in length between both resonances and she had half a wavelength then. And use the formula to find the speed with the wavelength?

Q7, sensors were located in the retina, right?

Q10, speed of ambulance was 1.1 ms??

Q.1 I also said friction, thought of gravity but couldn't remember how it affected it. I said somthing like air resistance, so use an aerodynamic rider. Don't think I'm right there though.

Q.10, I definitely got higher than that for the speed, something like 28/29m/s...good chance I'm wrong I'd say.

FatRat

29m/s is very quick though, isn't it?

Sounds right actually.

aleatorio

FatRat wrote: »

29m/s is very quick though, isn't it?

Sounds right actually.

Yeah that's right I'd say, about 100km/h

jimbob95

differences between a capacitor and a battery anyone? i said a capacitor can be recharged while a primary battery cant?

Huell

aleatorio wrote: »

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 )

for 11 you have to divide the frequency by 2 as two photons are produced.
I share 90% of your answers you have there

Huell

I got an A2 in the mock applied maths and got q6 wrong.....im an idiot

Daithi MacG

jimbob95 wrote: »

differences between a capacitor and a battery anyone? i said a capacitor can be recharged while a primary battery cant?

I said a battery converts chemical to electrical while capacitor stores electrical. And I said that a capacitor dishcharges very quickly in comparison.

aleatorio

jimbob95 wrote: »

differences between a capacitor and a battery anyone? i said a capacitor can be recharged while a primary battery cant?

I said that, and said batteries are chemical based and capacitors are electrostatic

Huell wrote: »

for 11 you have to divide the frequency by 2 as two photons are produced.
I share 90% of your answers you have there

I did divide by two though?

Nicke011

marno21 wrote: »

For q5, the way it said an hour, did you not have to multiply your U value by 3600?

Sorry forgot to write that, 75.6 * 24 * 60 * 60 = 75.6 * 3600 = 272160 Watts or Joules/second
EDIT: ****, I think I multiplied it with 24 for a whole day xD fuuuuu


@FatRat

Daithi MacG wrote: »

Q.10, I definitely got higher than that for the speed, something like 28/29m/s...good chance I'm wrong I'd say.

jimbob95

would the fact that capacitance is measured in farads and a battery in volts be valid haha :P

JackH14

For the frequency question in Q11 I got 1.2356 x 10^20 Hz. Did anyone else get that?

b0gg3r

JackH14 wrote: »

For the frequency question in Q11 I got 1.2356 x 10^20 Hz. Did anyone else get that?

Can't remember exactly what I got, but was in that region and was definitely x10^20Hz

FHB

JackH14 wrote: »

For the frequency question in Q11 I got 1.2356 x 10^20 Hz. Did anyone else get that?

I think I got that. It was something times 10 to the power of 20 anyway.

I thought that seemed about right. Similar to the answer in 2012's pair annihilation question.

qweerty

jimbob95 wrote: »

would the fact that capacitance is measured in farads and a battery in volts be valid haha :P

Spelt differntly... Pronounced differently... There are loads of them!

deadpixel

JackH14 wrote: »

For the frequency question in Q11 I got 1.2356 x 10^20 Hz. Did anyone else get that?

Yes I remember that cause it started with 123 haha. Was just mc^2/h I think, nothing too difficult,

Solid_Shepard

Nicke011 wrote: »

Lovely paper, it went unexpectedly good
Hoping for a A2/B1/B2

The marking scheme is probably going to be very rough

Q2 1.47
Q4 26
Q5 U-value, go construction studies!
Q6 Net force = 0, golfer is not moving;
Max height 12. something (about 13 as far as I remember); Let's go applied maths!
Q8 Engineering all the way!
238/92U + 1/0n = 239/95Pu + 2*(0/-1e)
Q12
b) V=-4.28cm
c) T=15.68 degrees

Just to nitpick for question 6, the net force is correct but your deduction is incorrect. As there is no net force it means that there is no acceleration, and, therefore, the trolley is at a constant velocity (the golfer is not necessarily stationary as it doesn't say it's at rest).