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Author Topic: CIE AS PHYSICS PAPER 1 (OCT/NOV)  (Read 14288 times)

Offline Tyserius

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Re: CIE AS PHYSICS PAPER 1 (OCT/NOV)
« Reply #15 on: November 12, 2009, 07:41:17 pm »
Quote from: falafail on November 12, 2009, 07:40:08 pm
aw, crap. i hate inequalities.
i'll think about it.  :(

Heheh :P I'll post more questions tomorrow after our paper or maybe during the weekends for the sake of our Paper 2 :D So, just try this first xD
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Offline falafail

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Re: CIE AS PHYSICS PAPER 1 (OCT/NOV)
« Reply #16 on: November 12, 2009, 07:52:57 pm »
Quote from: Tyserius on November 12, 2009, 07:41:17 pm
Heheh :P I'll post more questions tomorrow after our paper or maybe during the weekends for the sake of our Paper 2 :D So, just try this first xD
this is more like a mechanics question than a physics question, though..
i'll figure it out tomorrow XD
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Offline kavish

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Re: CIE AS PHYSICS PAPER 1 (OCT/NOV)
« Reply #17 on: November 13, 2009, 04:50:34 am »
lol nice question okiz after the paper i will do this one :D
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Offline jademax

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Re: CIE AS PHYSICS PAPER 1 (OCT/NOV)
« Reply #18 on: November 13, 2009, 06:02:01 am »
Hello all, could u pls help me with this question?
Quote
In a simple electrical circuit. the current in a resistor is measured as (2.50± 0.05)mA. The resistor is marked as having a value of 4.7 ohms ± 2%

If these values were used to calculate the power dissipated in the resistor, what would the percentage uncertainty in the value obtained

A 2%       B 4%        C 6%          D8%          

« Last Edit: November 13, 2009, 06:04:10 am by jademax »
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Offline falafail

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Re: CIE AS PHYSICS PAPER 1 (OCT/NOV)
« Reply #19 on: November 13, 2009, 06:09:39 am »
Quote from: jademax on November 13, 2009, 06:02:01 am
Hello all, could u pls help me with this question?

Quote
In a simple electrical circuit. the current in a resistor is measured as (2.50± 0.05)mA. The resistor is marked as having a value of 4.7 ohms ± 2%

If these values were used to calculate the power dissipated in the resistor, what would the percentage uncertainty in the value obtained

A 2%       B 4%        C 6%          D8% 


is it A?  :-\
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Offline highly_ambitious

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Re: CIE AS PHYSICS PAPER 1 (OCT/NOV)
« Reply #20 on: November 13, 2009, 06:17:59 am »
THE ANSWER IS B
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Offline jademax

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Re: CIE AS PHYSICS PAPER 1 (OCT/NOV)
« Reply #21 on: November 13, 2009, 06:21:22 am »
The answer is actually C... i also got B before. It took me a long time to try and figure why it is C but couldn't. Not even my super genius tution teacher could figure it out
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Offline falafail

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Re: CIE AS PHYSICS PAPER 1 (OCT/NOV)
« Reply #22 on: November 13, 2009, 06:22:51 am »
Quote from: jademax on November 13, 2009, 06:21:22 am
The answer is actually C... i also got B before. It took me a long time to try and figure why it is C but couldn't. Not even my super genius tution teacher could figure it out
what paper is this?
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Offline jademax

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Re: CIE AS PHYSICS PAPER 1 (OCT/NOV)
« Reply #23 on: November 13, 2009, 06:25:58 am »
May/June 2004
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Offline falafail

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Re: CIE AS PHYSICS PAPER 1 (OCT/NOV)
« Reply #24 on: November 13, 2009, 06:35:54 am »
okay, i don't know about the answer, but did you remember to divide the uncertainty by the actual value that you get for P? to get the percentage uncertainty..
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Offline Tyserius

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Re: CIE AS PHYSICS PAPER 1 (OCT/NOV)
« Reply #25 on: November 13, 2009, 06:53:00 am »
It's actually pretty simple.. Haha. Well you do know that Power = RI^2. So the percentage uncertainty for Power would be = Percentage Uncertainty of R + 2 ( Percentage Uncertainty of I ) << Because it is I^2 meaning I x I. You would get 2% + 2 (2%) = 6% which is C :)

P.S : If you wanna know how to derive the formula for percentage uncertainty, lemme know :)
« Last Edit: November 13, 2009, 06:55:12 am by Tyserius »
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Offline MaNi_DaDuDe

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Re: CIE AS PHYSICS PAPER 1 (OCT/NOV)
« Reply #26 on: November 13, 2009, 06:58:10 am »
Quote from: Tyserius on November 13, 2009, 06:53:00 am
It's actually pretty simple.. Haha. Well you do know that Power = RI^2. So the percentage uncertainty for Power would be = Percentage Uncertainty of R + 2 ( Percentage Uncertainty of I ) << Because it is I^2 meaning I x I. You would get 2% + 2 (2%) = 6% which is C :)

P.S : If you wanna know how to derive the formula for percentage uncertainty, lemme know :)

Yep.

Multiplying or dividing unc --> add
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Offline jademax

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Re: CIE AS PHYSICS PAPER 1 (OCT/NOV)
« Reply #27 on: November 13, 2009, 06:59:13 am »
ahh i see now.. thanks alot mate
This is wat i did:
P=I^2R but then i said 2(0.05/2.50)+0.02/4.7 =0.04

then 0.04*100=4%
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Offline jademax

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Re: CIE AS PHYSICS PAPER 1 (OCT/NOV)
« Reply #28 on: November 13, 2009, 07:01:54 am »
how do u get 2% as uncertainty for I?

Could u pls show me step by step
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Offline falafail

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Re: CIE AS PHYSICS PAPER 1 (OCT/NOV)
« Reply #29 on: November 13, 2009, 07:02:17 am »
well that was simple ._.
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