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Physics P42 answers

S

supermagic

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well, it'e been 24hours and we can talk about it now !!
here is some my answers plz check if it's correct :)
- gonna post only calcalus based question, not qualitative questions.

1. the ratio was 4.0 times ten to the power of something , cant remeber, but it was positive.(not sure if it's correct :S)
2. the number of mol, mine was 0.72, sth lyk that(not sure lol)
3. the capacitance was 1800 micro farad (by using gradient) and the energy, can't remeber. but easy to get by using W=1/2 CV^2
4. how about the capacitance with question, 12V between AB, i couldn't get it (it was asking for charges on capacitor X)
5. the alternating voltage question, I=9.9sin(380t) , i got the frequency, 60.5 and the rms values, 7.0 ampere. and the resistance, can't remeber but it was easy(knowing the fack that <P>=1/2 x I^2 / R
6. binding energy, 1u is equal to 930Mev, go check ur text book, it's in there. by using E=mc^2 then diviede by 1.6 x 10^(-13)
7. the op-amp question, the V1?V2? , i got 4.0 v and the magnitude of V out, i got 0.128, sth lyk that. ( got -0.128 but asking for magnitude so i put positive....is this correct?)
the rest of binding energy question, i cant sure about it or more likey doubt my answers, cuz it was straigh forward.( thought it was so easy compared to other binding energy questions....)
what else? the attenuation question, i think it was so easy and high marks (each 3 marks, 2 questions), but cant remeber the answer.
GT will not be higher than 70........ hopefully :)
 
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supermagic

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nisurju said:
thank u!r u sure ur ans 3 is correct?cant we add and calculate the mol?
Click to expand...
did u mean by question2? i am sure the question 3 is correct, the capacitance is 1800 micro farad.
by using the gradient, so (18 x 10^-3) - (9 x 10^-3) then divided by 5v gives me 0.0018 farad, which is equal to 1800 farad.
if u meant by q3, i am not sure, but the only way i could calculate, was using pV=nRT, and find each n, then add them together...
 
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nisurju

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yeah.everyone has done that way! :(
i took the sum of volume and temperature.n used that formula and calculated the no of moles
 
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zahraahmed

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why can't the threshold be higher than 70? the examiner can do anything if he goes crazy that includes v.v.v.v.strict marking this time! :(
 
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zahraahmed

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hahaha.............just try to think if paper 4 is this easy..............HOW TOUGH will be paper 5 :O :O :O
 
Xam

Xam

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supermagic said:
well, it'e been 24hours and we can talk about it now !!
here is some my answers plz check if it's correct :)
- gonna post only calcalus based question, not qualitative questions.

1. the ratio was 4.0 times ten to the power of something , cant remeber, but it was positive.(not sure if it's correct :S)
2. the number of mol, mine was 0.72, sth lyk that(not sure lol)
3. the capacitance was 1800 micro farad (by using gradient) and the energy, can't remeber. but easy to get by using W=1/2 CV^2
4. how about the capacitance with question, 12V between AB, i couldn't get it (it was asking for charges on capacitor X)
5. the alternating voltage question, I=9.9sin(380t) , i got the frequency, 60.5 and the rms values, 7.0 ampere. and the resistance, can't remeber but it was easy(knowing the fack that <P>=1/2 x I^2 / R
6. binding energy, 1u is equal to 930Mev, go check ur text book, it's in there. by using E=mc^2 then diviede by 1.6 x 10^(-13)
7. the op-amp question, the V1?V2? , i got 4.0 v and the magnitude of V out, i got 0.128, sth lyk that. ( got -0.128 but asking for magnitude so i put positive....is this correct?)
the rest of binding energy question, i cant sure about it or more likey doubt my answers, cuz it was straigh forward.( thought it was so easy compared to other binding energy questions....)
what else? the attenuation question, i think it was so easy and high marks (each 3 marks, 2 questions), but cant remeber the answer.
GT will not be higher than 70........ hopefully :)
Click to expand...

1. 10*36
2. mine were 300 smething :cry: :cry: :cry:
3. yes 18 i guess
4. first divide the voltage as it was series circuit, then find capacitor and divide by 2!!!!
5.yes freq 60.47, rms 7A, resisitance by Power formula as it was mean so had to use Ipeak value....
6. it was easy
7. yes even i got 4, 2nd part i dont know
 
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ima_shah2002

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yea for da first one 10 raised to 36... second also.0.72mol..3rd.. 1800 microF.. i got same values frequency and rms... for the mean power we could use P=0.5I^2 R but also its equal to P=Irms^2 R so i think i woulda done that right...
For the one with capacitcance between AB... first u find total capacitance of parallel = 10 + 10= 20Kkohm then in series so 20x10/(30) = 6.67kohm .. in series current and charge is constant.... therefore Q=CV so 6.67x12= 80 so that is charge...
the attenuation question i think i got lenght as 70.5 km... and btw for the V1 V2 thing i made a silly error of considering 1025 and 1028... and so my final answer was -0.154... but -0.128 is correct.. how many marks would i lose if i am damn sure my method was correct...
For the internal energy thing... in vaporisation particles need to me moved alot further apart than fusion..so pe needs to be raised more.. more latent heat required.. secondly since gas will have a greater volume more work is done BY the gas so U=Q+(-W) so the more negative the work done.. the greater is the value for q...
By the way is ionosphere not preferred...
 
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supermagic

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oh dammm, ur answer in q2 is 300???? did u change cm^3 to m^3???? the volume was in cm^3 so u gotta change it!!
 
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filza94

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Topic To Stress On Biology Paper 33 AS
Gaseous exchange
Infectious diseases
Immunity
Transport: In plants- all the pathways in the cell (apoplast n symplast)
in humans- cardiac cycle, pressure graph, etc...
Nitrogen cycle

Itx surely cuming as my Biology Teacher predicted them every year she does n it cumss last year 4 my O level also she predict so i got A* n dat all camee now she precdicted for AS Paper 33 so evryone study all topics anyway so focusing on these shouldn't make u forget the others!!!!
 
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boy2011

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i forgot to change cm^3 to m^3.other wrkng was perfect so how many marks will i loose???????plsssss tell me..i thnk il lose 1 mark??as answer will be wrong other working was ok..?
 
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blueindigo

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Which variant is this???? there was no capacitance, nor latent heat , no binding calculation energy..seems like i had a very diff variant!!!
 
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