A2 Physics:- Help Ideal gases Paper 4
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A2 Physics:- Help Ideal gases Paper 4November 2009 Paper 42 - Attached9702_w09_qp_42.pdf
Question 2 c ii)
Marking scheme says that this question was deleted for insufficient information in question. What is the missing information? because I solved it and was surpriesed to know that it was omitted.Last edited by The_Aviator; 13-05-2012 at 09:37. -
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Re: A2 Physics:- Help Ideal gases Paper 4why cant we use U = Ek + Ep and Ep = 0(Original post by JonathanM)
U = Mass x Specific Heat Capacity x change in temperate.
or rather
E = mcΔø
You did not have the mass or specific heat capacity
Only U which = 30J.
So U = 3/2 k T ? -
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Re: A2 Physics:- Help Ideal gases Paper 4Im sorry for using your time, but I mean Delta U = 3/2 k Delta T(Original post by JonathanM)
Because you already have the energy but you don't have the mass or specific heat capacity lol. You're finding change in temperate "Δø"
30 Joules = 3/2 x (8.314 / 6.02x10^23 ) x Delta T? Why wont this work? -
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Re: A2 Physics:- Help Ideal gases Paper 4I mean I cant understand why you used this formula?(Original post by JonathanM)
U = Mass x Specific Heat Capacity x change in temperate.
or rather
E = mcΔø
You did not have the mass or specific heat capacity
Only U which = 30J.
Why cant we use U = Ek? or U = P x Delta V = n R x Delta T?? -
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Re: A2 Physics:- Help Ideal gases Paper 4In this case where no PE exists as inter-molecular bonds are ignored. U = (3/2)Nkt = M C delta T
(3/2)kt or 1.5pV/N or 1.5nRT/N is the kinetic energy for a single particle lol. U is the total KE of the whole system 0.5Nm(v^2)
For all processes energy is of ORDER kT. We have specific equations for U like U = 1.5pV or 1.5Nkt or 1.5nRtLast edited by JonathanM; 13-05-2012 at 18:05. -
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Re: A2 Physics:- Help Ideal gases Paper 4Sir, I am sorry bt may you provide a more detailed , simpler explanation?(Original post by JonathanM)
In this case where no PE exists as inter-molecular bonds are ignored. U = (3/2)Nkt = M C delta T
(3/2)kt or 1.5pV/N or 1.5nRT/N is the kinetic energy for a single particle lol. U is the total KE of the whole system 0.5Nm(v^2)
For all processes energy is of ORDER kT. We have specific equations for U like U = 1.5pV or 1.5Nkt or 1.5nRt
I cant seem to understand why cant we use U = 3/2 R/Na x T
or P delta V = U = N x k x Delta T.
I am really confused as to which formula to use and why you used mc delta T. -
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Re: A2 Physics:- Help Ideal gases Paper 4I already finished preparing for tmrw's exam. but then i came across this(Original post by JonathanM)
It's the only one that gives us a change in temperature in g494
.
What are you confused about?
Work done calculated is 30 Joules by P x delta V!
Internal energy of ideal gas at constant T = work done!
So U = P x Delta V. We are agreed on this.
Questions/Confusion:-
calculating temperature change.
1 - Is it possible to use the formula U = total change in kinetic energy
so 30 joules = 3/2 x N x k x Delta T ? If no, why not?
2- Is it possible to use the formula
U = work done = P x Delta V = n x R x Delta T? If no , why not?
Why is there a difference between P Delta V = n R Detla T
and P Delta V = 3/2 n R Delta T
When I am just using Thermodynamic laws?
Please help me address each one seperately with simple clear explanation to close this matter efficiently! Thank you!
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Re: A2 Physics:- Help Ideal gases Paper 4we dont have a paper 6 for a2!(Original post by deathb4dishonour)
Can someone please explain the formulas of percentage uncertainty to use in different situations for A2 physics paper 6. I have the paper 6 exam next monday .......so please reply fast!!!!! -
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Re: A2 Physics:- Help Ideal gases Paper 4You've missed out the number of atoms -> U = 3/2 nRT (n = no. moles, which you are given)
Yes, you can do it if you know this, but the reason the question is removed is that you don't know the heat capacity because you're not expected to know equipartition theory. (As in you're not expected to know the 3/2kT per particle factor) It won't be on the syllabus. You've been taught it as an extra.
You could use the ideal gas equation I reckon, if you assume that pressure remains constant (which you sort of have to do for the first part) -
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Re: A2 Physics:- Help Ideal gases Paper 4Help me in this question in link below please. Its about resonance!(Original post by Stonebridge)
The question is impossible because to calculate the work done by the gas expanding you need to know either its initial temperature or pressure. Neither is given.
Atmospheric pressure is given but is irrelevant.
http://www.thestudentroom.co.uk/show...7#post37721777
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