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AQA Physics PHYA4 - Thursday 11th June 2015 [Exam Discussion Thread]

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Original post by NEWT0N
What is it out of again?


75
Original post by Fred Cantoni
It said assume string is horizontal though



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Ah right yeah i see, **** !
Original post by kevincarreira
First one is weight

June 11 paper
ImageUploadedByStudent Room1434020322.932684.jpg


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Original post by Alexie56
Surely if they were charged with the same voltage the initial current should be the same. They were juat discharged through different resistors. So I drew a shallower graph?😕


thought of V=IR, so initial current would be less
Original post by NEWT0N
There were 3? Hm, maybe they would want you to extend the graph to cover the whole length of the x-axis or something. Or they would not want it to intercept the x-axis but only tend asymptotically to it. I don't know


Yeah I thought so?

Erm yeah that would be likely, if they have really made a typo they might just omit the question though...

How was the rest of the paper for you?


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Fe27
3
Why did I get around 31nC for the charge?? I found the gradient and multiplied by the constant
Original post by QueNNch
Thanks for putting them!

I think you question 17 is incorrect because the question asked for the number on electrons on the NEGATIVE plate ONLY. Therefore the answer is half of what you got. (something like 2.2 x 10^10)

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Q 22 i got 1/root 2
Original post by Fvthoms
55 for A*
50 for A
etc...


Hmmm just out of curiosity why'd ya 55 for A*?

Last it was 61/75 do you think this exam was significantly harder than last year.

Coz i dont know if i found harder than last year after reading peoples comments
I thought the same, and also, the capacitance is the same. I started mine at the same current level and ended it above the other graph.

Original post by Alexie56
Surely if they were charged with the same voltage the initial current should be the same. They were juat discharged through different resistors. So I drew a shallower graph?😕
Original post by NEWT0N
No time period isn't affected because it only depends on the length of the spring and a simple pendulum is isochronus.

I put the time period stays the same and there is a larger restoring force because the weight is greater at maximum amplitude so the horizontal compoent of weight (restoring force) is larger. But then I went on to say something silly like how this causes a smaller amplitude, but I think it should be a bigger amplitude? My thinking is still a bit cloudy after the exam so I'm hoping someone can clarify this for me! :smile:


I also wrote about a larger restoring force, hence a larger energy loss due to resistive forces, which would result in heavier damping. Don't know if it's correct or not...
Original post by NEWT0N
No V=IR so I=V/R is proportional to R since V is constant. R increases so 1/R decreases, hence I is smaller.


They were charged through the same circuit in the exact same way though I think so the initial current is the same. When it discharges it goes through a different circuit with the resistor. Not entirely sure though
Original post by DannySmith420
Q 22 i got 1/root 2


Same!
Original post by Mehrdad jafari
Here are my answers. The ones I'm not sure with i have mentioned next to them.

I have failed to take the answer of one of the MC questions. Let me know if you found which one.
I would be very happy if you could correct the ones that are not right :smile:
ImageUploadedByStudent Room1434019809.052314.jpg


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1. Is newtons as rate of change of momentum is force (newtons 2nd law)
21. I put A as it had the longest side perpendicular to the magnetic field. Its a couple and not looking for flux (so largest area is irrelevant) force on couple is F=BIl so biggest couple was A as it had largest length perpendicular to field
22. I think is 1/root 2 as kinetic energy is proportional to the square of velocity
anyone else get like DDDAAA near the end?
Past grade boundaries:1434020555233.jpg

I reckon
51 for A
57 for A*
On 2nd law points I talked about how ma is mv^2/r due to v^2/r being the centripetal acceleration
Original post by NEWT0N
It went well but I was disappointed at the sheer number of repeats from previous papers which probably gave people who did lots of past papers (including me) a slight advantage on time taken to complete the paper.


Yeah the multiple choice certainly felt quite familiar! Ah well long time to wait to find out how we acc did, good luck!


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Original post by QueNNch
Alright guys I drew my graph like this

1434019524377.jpg

I think in probably wrong because the initial current (y axis) would be lower.

Thoughts?


Totally wrong as gradient should also be shallower due to higher RC. Don't think they'll include the question though as it was worded incorrectly should have been 300ohm not 300kohm
Original post by NEWT0N
Thanks, are the grade boundaries usually that low? (I don't check them)


At the beginning of the spec the grade boundaries were pretty low. You could lose 12 marks and get full UMS.

But last year its gone up a bit.

It was 61/75 for an A* and 69/75 to get full UMS.
(edited 8 years ago)
this one was definitely harder than last year - we're so pressed for time in this exam its so annoying. gonna have to boss phya5

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