IGCSE/GCSE/O & A Level/IB/University Student Forum
Qualification => Subject Doubts => GCE AS & A2 Level => Sciences => Topic started by: falafail on May 22, 2010, 01:37:24 am
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DO NOT POST ANYTHING HERE EXCEPT QUESTIONS RELATED TO PHYSICS PAPER 4 OR I WILL MURDER YOU >:( >:( >:(
okay, so:
1) june 02 Q 4b
2) nov 05 Q 4b in the markscheme it says "endpoints of line correctly labelled" what are we supposed to label exactly???
3) june 06 Q 4c
4) nov 02 Q 1a how do we do (i)? and for (ii) why do we use 7 minutes and not 9?
5) june 04 Q 2b(ii) and for Q6 the last row is like + + 0, but shouldn't it have been 0 + -, 'cause the particles move so they're doing work??
6) june 06 Q 2b(ii)
7) how do you determine the amplitude from a ke/pe graph?
HELP :(
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1) The EP graph NEVER GOES NEGATIVE. So A t=0 it is max.. At t= 0.025 approx, it is 0.. It reaches Max again at at t=0.05
2)Label The maximum and minimum displacement.
3)Max Speed--> Horizontal ( right / left ) part of the circle Max Accel--> The uppermost vertical part of circle
4) Use the formula Power x Time ( 2min ) = mass x specific heat x ( 100 - 20)
FOr part 2, We use 7, cause only at that time the water starts boiling. Only for the last 7 min that the temperature is constant. So we can apply Q=mL
5)Use formula p=1/3 (density) ( Mean square speed )
NO. FOr the box thing. THERE IS NO WORK DONE. W=pdV. No change in volume. So no work done.
We know Q must be +.. SO leaving U must be +. Alternatively, working from U. No change in Temperature. But Their state changes, thus their EP increases. REMEMBER THIS IS NOT IDEAL GAS, SO EP CANNOT BE NEGLECTED.
6)Use pV=nRT for the balloon too. And Compare No of moles with part a.
7) KE/PE graph against what?? Usually we do displacement. So, Just look for the Max EP and down to the x axis. Thats the amplitude.
HOPE IT HELPS!!!!! ;D
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cn someoen xlain the graph of q7 part 1 june 2005.??
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cn someoen xlain the graph of q7 part 1 june 2005.??
Half-life is the time for undecayed atoms to be reduced by half. So the graph would be an exponential growth, starting from origin. At t = 2.6, mass of Fe-56 would be 1/2(1.4) = 0.7 micrograms
Mass of Fe-56 would increase over time, so at another 2.6 hours (t = 5.2), mass = (0.7) + 1/2(0.7) = 1.05 micrograms and so on ...
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Thanks...:)
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1) The EP graph NEVER GOES NEGATIVE. So A t=0 it is max.. At t= 0.025 approx, it is 0.. It reaches Max again at at t=0.05
2)Label The maximum and minimum displacement.
3)Max Speed--> Horizontal ( right / left ) part of the circle Max Accel--> The uppermost vertical part of circle
4) Use the formula Power x Time ( 2min ) = mass x specific heat x ( 100 - 20)
FOr part 2, We use 7, cause only at that time the water starts boiling. Only for the last 7 min that the temperature is constant. So we can apply Q=mL
5)Use formula p=1/3 (density) ( Mean square speed )
NO. FOr the box thing. THERE IS NO WORK DONE. W=pdV. No change in volume. So no work done.
We know Q must be +.. SO leaving U must be +. Alternatively, working from U. No change in Temperature. But Their state changes, thus their EP increases. REMEMBER THIS IS NOT IDEAL GAS, SO EP CANNOT BE NEGLECTED.
6)Use pV=nRT for the balloon too. And Compare No of moles with part a.
7) KE/PE graph against what?? Usually we do displacement. So, Just look for the Max EP and down to the x axis. Thats the amplitude.
HOPE IT HELPS!!!!! ;D
THANK YOUU :D
but...
2) where exactly are those?
3) why? explain please.
6) that's what i did but i got it wrong :-\ could you work it out?
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2) Both ends of your line graphs.
3) Max Speed happens when displacement=0. All of the Ep is converted to Ek when d=0. And thats when the pivot is at the horizontal part.
Max Accel. happens when Ep= max. When displacement=max too. Because a=- (omega)^2 . (displacement)
Accel is then directly but in opp. direction to displacement.
6)Sorry. I was careless before. Here is the right way==
volume of gas at 1.85 × 10^5 Pa = (2.5 × 10 × 4.00 × 10 ) / (1.85 × 10)
= 5.41 × 10 ^6 cm^3
5.41 x 10^6= 4x10^4+(7.24 x 10^3)(N)
N= 740
The method which was wrong, is that we assume both cases (in cylinder and balloon) have the same pressure. But they do not. You must get 747 at the beginning. AFter doing this type of question, its very assuring to do it by another method aside pV=nRT.. Say p1v1=p2v2 and so on.
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3) Max Speed happens when displacement=0. All of the Ep is converted to Ek when d=0. And thats when the pivot is at the horizontal part.
Max Accel. happens when Ep= max. When displacement=max too. Because a=- (omega)^2 . (displacement)
Accel is then directly but in opp. direction to displacement.
but why is it when the pivot is at the horizontal part? :-\
also, i have more questions :(
8 ) why are values of gravitational potential near to an isolated mass all negative?
9) nov 03 Q 1a
10) june 05 Q 5b
11) how does a capacitor store energy?
12) june 05 Q 6b all of it -_-
13) nov 05 Q 5b (ii) 1 and 6c (ii)
14) june 06 Q 6c and 8b (ii)
15) specimen paper Q 3b (i) 1 + (ii) 2
16) june 02 Q 6 a
17) june 04 Q 5d (ii) why is it 3??
18) nov 06 Q 6b + c (iii) and 7b
i know they're a lot, sorry :(
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oh also, are we supposed to know the specifics about nuclear fusion and fission, and probing matter??
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AHHHHH SO MANYYYYYYY
AHAHAHAHHA
Add me at msn and i will try my best to help.
When the pivot is at the horizontal part the bar thing is halfway up and halfway down. so, displacement=0.
8)
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AHHHHH SO MANYYYYYYY
AHAHAHAHHA
Add me at msn and i will try my best to help.
When the pivot is at the horizontal part the bar thing is halfway up and halfway down. so, displacement=0.
8)
alright, what's your msn?
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bruce_lee_gibb@yahoo.com
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bruce_lee_gibb@yahoo.com
um, i added you and it was like, "two seperate accounts found for this person" o.O
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um, i added you and it was like, "two seperate accounts found for this person" o.O
falaFAIL, you're stealing my study buddy. :P
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falaFAIL, you're stealing my study buddy. :P
orly? is he any good? ;)
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is anyone of you kind enuf to answer this question?
physics paper 4 nov 2005 Q:6 c (ii)
please and thank you..
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is anyone of you kind enuf to answer this question?
physics paper 4 nov 2005 Q:6 c (ii)
please and thank you..
when t is between 0 and T: E is zero (i.e. horizontal line on the t-axis)
now for the second and third section - again is a horizontal line but it does not matter which way you put them as long as they are in opposite (i.e. 2nd might be below the t-axis and 3rd above the t-axis or vice versa)
but the third part needs to be double of the second part ...
I hope that makes sense :D
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thanks onion..(why onion?)
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thanks onion..(why onion?)
Its a name I used when I play COD 4 ;D and I love Onion Tou :D
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In jun 04 d.ii) why is it 3 ?!
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In jun 04 d.ii) why is it 3 ?!
It is not a sine wave. Square waves have the RMS equal to peak voltage. You have to accept this at A level.
For sawtooth voltage , for example, its RMS=Vo/( square root of 3). And so on.
You can check it out at wikipedia if you want to know the detail explanation
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Ok thank you I never knew about this.
Oh and could anybody please explain eddy currents to me ? I don't really get them where do they come from what do they do ... ??
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In jun 04 d.ii) why is it 3 ?!
Actually there is another way to think of it. First what is the rms value - its the Root Mean Square value
that means you Square all the values first (when you square - you'll get the value of 9 [both the -ve and +ve part])
then you take the Mean (mean of 9 is just 9 :D)
and last you take the Root (square root of 9 is 3 !! ;))
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What about june2009 q11.b)iii) .. I don't understand what they did :s
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And q6 June 2009 also part c) please .. To do with rms .. Which I'm really confused about !
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plz sm1 ans ma queries ??? ???
nov09/42
Q1 part (c)
Q3 part (c)
Q5 part a2
Q7 part b2
Q9 part c2
Q10 part a2
Q11 part c2
nov09/41
q5 part b2
Q6 part b1
Q10
Q12 part d
atleast sm1 ans sm of these ques if he cant all....plz i really need help in thm