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# AQA Physics PHYA5 - Thursday 18th June 2015 [Exam Discussion Thread] watch

1. (Original post by TheRAG)
If you're doing that then perhaps we should send you our answers?
If the answers I PMD'd you are correct you can use those
Course! Everyone is free to PM me if they wish so it can be compiled quicker

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2. Me too...with that P-V diagram question, wasn't the straight bit on the top to the left of the curve I calculated as well, decreasing in volume? Meaning work had to be done on the gas? Just trying to understand my flaw...[/QUOTE]

From what I learnt, if it goes from the right hand side to the left on the PV diagram, work is done on the gas because the gas is compressed. If the gas[/QUOTE]

Yeah...so that's why I included B-C? Confused now lol...don't matter anyway, I should hopefully only lose 2...
3. (Original post by eekeek)
.... and then square root it all?
Nah, that would give you the root mean square speed instead.

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4. (Original post by eekeek)
.... and then square root it all?
did it want mean squared speed, or root mean square speed?
5. [/QUOTE]
Me too...with that P-V diagram question, wasn't the straight bit on the top to the left of the curve I calculated as well, decreasing in volume? Meaning work had to be done on the gas? Just trying to understand my flaw...[/QUOTE]

From what I learnt, if it goes from the right hand side to the left on the PV diagram, work is done on the gas because the gas is compressed. If the gas expands, work is done by the gas meaning it goes form the left to the right.
6. From what I learnt, if it goes from the right hand side to the left on the PV diagram, work is done on the gas because the gas is compressed. If the gas expands, work is done by the gas meaning it goes form the left to the right.[/QUOTE]

Didn't B-C go right to left tho and so shiuld be included? What do you think full ums and A* boundary will be?
7. (Original post by eekeek)
.... and then square root it all?
square rooting would give you the root mean square speed, it asked for the mean square speed so don't square root
8. Don't know what's wrong with quoting.
9. (Original post by Vincent Song)
Don't know what's wrong with quoting.
No idea...
10. (Original post by Reverse Swing)
I've made an account just to tell you that it is UMS and not Ucas points lol.

Anyway thank you for the averages. I personally think that the A* would be around 55 for Unit 5A and 57 for Unit 4.
Oh yeah Silly me, I do know that so haven't got a clue why I put ucas.... Think it's been because I've been looking through my 'ucas' folder this morning lol!
11. (Original post by CD223)
Course! Everyone is free to PM me if they wish so it can be compiled quicker

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Hi, if your making an unofficial mark scheme please could you put the amount of marks each part is worth please (if you know the amounts) thanks
12. (Original post by Daniel....)
No idea...
Yes, I think B-C should be included. Basically, you had to calculate the area of the loop. Well, because I missed 5 mark question out, I have no idea what the boundaries will be. Lol... Hope it will be lower than last year, coz I need an A*......
13. (Original post by Vincent Song)
Yes, I think B-C should be included. Basically, you had to calculate the area of the loop. Well, because I missed 5 mark question out, I have no idea what the boundaries will be. Lol... Hope it will be lower than last year, coz I need an A*......
Right good...did you? I did the area under not just the loop...said net, so did the whole thing lol...
Yeah me too...where for for you? Imperial for me...
14. (Original post by Daniel....)
Right good...did you? I did the area under not just the loop...said net, so did the whole thing lol...
Yeah me too...where for for you? Imperial for me...
Same! Haha
15. (Original post by Vincent Song)
Same! Haha
Oh...so how come we got different answers?
16. (Original post by Daniel....)
Oh...so how come we got different answers?
I meant imperial .....
17. (Original post by Vincent Song)
I meant imperial .....
Oh...Maths?
18. I do applied and heres some of the maths answers i got god knows if they are right, anyone get similar??

3671 revolutions
5.52x10^-3
1.43x10^-3
430
75 for graph area
15750
0.63 or 63% for efficiency
7.62x10^7
19. (Original post by Mattyhouse)
I do applied and heres some of the maths answers i got god knows if they are right, anyone get similar??

3671 revolutions
5.52x10^-3
1.43x10^-3
430
75 for graph area
15750
0.63 or 63% for efficiency
7.62x10^7
Same bar the P-V graph which I got wrong I believe, then ovbiously power after that...got the same efficiency for last q but diff number after? Can't remember what it was...
20. (Original post by Vincent Song)
Yes, I think B-C should be included. Basically, you had to calculate the area of the loop....
Not saying I'm right but.... B-C was horizontal I think. So constant pressure. So no compression so no work done ON the fluid. That was my reasoning. Hey ho.

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