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

1. (Original post by chizz1889)
No you were correct the first time in saying there is the same amount of drag. Force is the same as rate of change of momentum of u can remember q1 on multiple choice. This means the same amount of drag will have the same rate of change of momentum. Since velocity is independent of mass the initial velocity is the same, as is the time period. But since the mass is larger and the rate of change of momentum is equal to before means that the rate of change of velocity is reduced meaning it takes longer to lose its velocity hence less damping
I agree, i see my mistake. I concluded that the drag force is the same, but I forgot what it was opposing (the momentum of the bob). So the drag force is NOT the damping force? I always thought this was the case with pendulums.
3. (Original post by chizz1889)
Preach 🙌🏻
Until my death
4. (Original post by l1lvink)
Just heard back from my school who called AQA; they have realised that its a mistake!!
Did you get any information how they're going to account for it by any chance?
5. Does anyone have a copy of the paper?
6. Can someone explain the answer to the rod in the two coils questions?
7. (Original post by l1lvink)
Just heard back from my school who called AQA; they have realised that its a mistake!!
There was a typo?!!? What are AQA doing about it??

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8. (Original post by l1lvink)
Just heard back from my school who called AQA; they have realised that its a mistake!!
what is?
9. (Original post by NEWT0N)
Did you get any information how they're going to account for it by any chance?
I think all they'll do is remove 1 mark because you can still get the other 2 for initial current and area under graph being less
10. typo : 150 ohm to 300K ohm
11. (Original post by Remiepascua)
what typo?
The first part of the question used a 150Ω resistor, and the second part a 300,000Ω resistor. This lead to a graph that could not be drawn accurately, as it had to start at 1/2000th of the height of the original line! Clearly they missed a 'kilo' off the 150Ω, or added one in on the 300kΩ.
12. I think
A* 60
A 52
B 46
etc etc
13. (Original post by Brown9)
Does anyone have a copy of the paper?
Lol

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14. (Original post by NEWT0N)
Cool, hopefully they won't penalize for not including exactly that as I don't think we even had to talk "quantitatively" anywhere in the question. (6-markers are qualitative assessments)

I do remember saying that the weight of the ball is much less than the centripetal force though (but I didn't justify this with a calculation)
Yeh usually in the markscheme there will be like 8-10 individual points, then 1 mark for written communication, and 1 for probably the use of a diagram.

Do you think 56/75 will be an A* or just a high A, i made loads of stupid mistakes. Hopefully I can bring it up in unit 5, and in my coursework i got full ums?
15. anybody else feel like they completely ****ed it?
16. (Original post by Amanzz)
I agree, i see my mistake. I concluded that the drag force is the same, but I forgot what it was opposing (the momentum of the bob). So the drag force is NOT the damping force? I always thought this was the case with pendulums.
Drag force is the damping force but damping is how it affects the system, not the size of the force. I got it wrong too but I think we will still get 1/3 each for saying the resistive force is still the same 😊
17. Yooooooo was the first answer weight??
18. (Original post by ChiefKeef)
Yooooooo was the first answer weight??
No it was D,
rate of change of momentum, KGms^-2 which is the same as Newtons
19. (Original post by Jed-Singh)
I think
A* 60
A 52
B 46
etc etc
Yeah sounds reasonable, could be a mark or two higher.
20. (Original post by Remiepascua)
has anybody got any good resources for info on resonance and damping? i have a feeling we'll get some tricky questions on this to catch people out
Haha you predicted this the day before the exam!

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