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

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Original post by JxckWilliams
For the 2 six markers for the main paper and then astronomy i put:
>have a system that you can change the temperature of a gas in a fixed container (therefore volume and moles is constant).
> starting from room temperature cool the gas and measure the pressure with a pressure gauge.
>Plot a graph of Pressure (Y) by Temperature (x) and draw a line of best fit, then extrapolate the line back to the x axis and this is where pressure will be 0 (the x axis was in celsius)
>"This is the temperature where there is no pressure. This means the particles are stationary as pressure arises from the particles colliding with the pressure gauge" (or some **** like that)

Astronomy:
>measure time period by looking for the time between 2 similar peaks.
>Measure the tangential speed for the orbit of each star by looking at the red shift.
>i then went on to explain how you could work out the radius of the orbit around the common centre of mass, as you have the tangential speed and you have the time period so just apply some phy4 oscillations equations etc (did anyone else say this?)


Do you remember if they asked us to calculate the speed and period or did they just ask how you would calculate it? I just explained the formulas and didn't substitute in the numbers to work out the values.
Reply 3801
Original post by Reverse Swing
Do you remember if they asked us to calculate the speed and period or did they just ask how you would calculate it? I just explained the formulas and didn't substitute in the numbers to work out the values.


It said describe how the speed and period would be determined from the graphs and include "suitable calculations" in your answer.


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Original post by CD223
AQA, OCR and Edexcel do theirs the day before. WJEC is different each year - sometimes not updating until actual results day.


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yeah, that's more like it
Reply 3803
Original post by Mehrdad jafari
yeah, that's more like it


How did you feel PHYA5 was compared to PHYA4?


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Original post by xuyixuanpbs
Yeah right I think I wrote sth stupid in physics exam, a 6 marks question asking how to determine absolute zero. I never revise it as it only occupies such a tiny space in the book and I never pay attention to it.

I put down use a kelvin thermometer and a Celsius thermometer to measure the temperature of a fixed amount of gas respectively.... then work out the difference....the subtract the difference from 0......

Bull****. If a kelvin thermometer is based on the concept of absolute zero...then what is the point to use it to determine absolute zero... I rethink after the exam and feel the answer is stupid...

I did also put down absolute zero is when the mean kinetic energy of all gas molecules becomes zero so does their root mean square speed is zero so it's actually impossible. And the experiment should be carried at constant pressure with a fixed mad and volume of gas. Take repeats and average. Honestly how many marks will I lose for this question I feel so regretful and scared:frown:


to be honest that's not that bad, at least you tried take the short cut but you neglected that the kelvin temperature was calibrated on the basis of absolute zero itself. You do get some marks for saying that the mean kinetic energy of the molecules of the gas reaches zero, regardless of whether the mean or the root mean square speed of the molecules is zero.

Don't worry about it man. of course some people might think they have done well on the six marker but when it comes to looking at the mark scheme then the situation is different.
Original post by CD223
How did you feel PHYA5 was compared to PHYA4?


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I think on average it was quite the same. The six marker for turning points was in the middle of the questions and so because I spent more time on it that i should have, i ended up having not enough time for the last question so i missed a few marks. I think I was quite obsessed with six marker in turning points but I'm sure i got the marks I wanted to :smile:

How did you find it?
Reply 3806
Original post by Mehrdad jafari
I think on average it was quite the same. The six marker for turning points was in the middle of the questions and so because I spent more time on it that i should have, i ended up having not enough time for the last question so i missed a few marks. I think I was quite obsessed with six marker in turning points but I'm sure i got the marks I wanted to :smile:

How did you find it?


Ah that sounds like the opposite of me! I did all of the other questions in both papers before attempting both six markers back to back haha!

It was an.. Interesting paper. Made so many mistakes on both units so I think I'll get an A instead of an A* :/ but who knows :s-smilie:


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Original post by CD223
Ah that sounds like the opposite of me! I did all of the other questions in both papers before attempting both six markers back to back haha!

It was an.. Interesting paper. Made so many mistakes on both units so I think I'll get an A instead of an A* :/ but who knows :s-smilie:


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The same here. I did make so many mistakes too but to be honest I'm not very surprised by that as I literally closed my eyes and hoped that whatever i wrote was correct lol

edit: some of my class mates doing astro did find the astro unit somewhat weird though
(edited 8 years ago)
Original post by Sbarron
Thanks


no worries!
Original post by Mehrdad jafari
no worries!


You get the papers today right?
Original post by ubisoft
You get the papers today right?


oh, no. sorry i didn't realise yesterday was Friday. I meant the Saturday next week because yesterday i would have said I will have the paper by tomorrow and not Saturday. I said Saturday because i looked at the date on my calender :frown:
Original post by Mehrdad jafari
oh, no. sorry i didn't realise yesterday was Friday. I meant the Saturday next week because yesterday i would have said I will have the paper by tomorrow and not Saturday. I said Saturday because i looked at the date on my calender :frown:


oh alright haha
Reply 3813
Original post by Mehrdad jafari
The same here. I did make so many mistakes too but to be honest I'm not very surprised by that as I literally closed my eyes and hoped that whatever i wrote was correct lol

edit: some of my class mates doing astro did find the astro unit somewhat weird though


Hahahah yeah I know what you mean. Astro was weird compared to previous years. I'm hoping it's a fairly low boundary like last year.


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Original post by CD223
Hahahah yeah I know what you mean. Astro was weird compared to previous years. I'm hoping it's a fairly low boundary like last year.


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yeah, the grade boundaries won't shift by more than 1 or 2 marks
Original post by Mehrdad jafari
yeah, the grade boundaries won't shift by more than 1 or 2 marks


You think the GB will be same as 2014? you have any idea why they were so low?
Original post by ubisoft
You think the GB will be same as 2014? you have any idea why they were so low?


yeah, they should be. I have no idea why the GB for the unit five is lower than unit 4 but my understanding would be that students don't get to revise unit 5 as much as unit 4 because on average unit 4 is taught first at colleges and more practice is done on it than unit 5. Maybe
Reply 3817
Original post by Mehrdad jafari
yeah, they should be. I have no idea why the GB for the unit five is lower than unit 4 but my understanding would be that students don't get to revise unit 5 as much as unit 4 because on average unit 4 is taught first at colleges and more practice is done on it than unit 5. Maybe


Our college certainly focused more on unit 4. Maybe because it's the bigger unit in terms of core content and usually has higher boundaries so requires more knowledge to get a better grade. Odd chicken and egg cycle haha.


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Original post by CD223
Our college certainly focused more on unit 4. Maybe because it's the bigger unit in terms of core content and usually has higher boundaries so requires more knowledge to get a better grade. Odd chicken and egg cycle haha.


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that's true as well
Original post by CD223
Our college certainly focused more on unit 4. Maybe because it's the bigger unit in terms of core content and usually has higher boundaries so requires more knowledge to get a better grade. Odd chicken and egg cycle haha.


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You think section A was harder or easier than last year? I hope the boundary will be about the same as last year. (I did the applied one though)

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