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# AQA Physics PHYA4 - 20th June 2016 [Exam Discussion Thread] watch

1. (Original post by Charlie1523)
Can someone help me with this question: Question 9 http://filestore.aqa.org.uk/subjects...1-QP-JAN13.PDF thanks
There is a formula for it. x(n+1) = yn, where x is the pendulum with the shorter time period. In this case:
1.90(n+1) = 1.95n
1.90n + 1.90 = 1.95n
0.05n = 1.90 therefore n = 1.9÷0.05 = 38 oscillations.
2. (Original post by Yo12345)
Attachment 553000

Just to clarify. Is no work done when a charge moves perpendicular to a uniform electric field? Is work only done when the charge moves parallel to the field lines?

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3. (Original post by spanisholive)
There is a formula for it. x(n+1) = yn, where x is the pendulum with the shorter time period. In this case:
1.90(n+1) = 1.95n
1.90n + 1.90 = 1.95n
0.05n = 1.90 therefore n = 1.9÷0.05 = 38 oscillations.
Thanks Does this formula apply for all situations regardless of the time difference between oscillations?
4. (Original post by SirRaza97)
Cheers i understand it now thanks.
5. (Original post by alevelstresss)
Gravitational field strength is a vector quantity, given by g = GM/r2

Make the two field strengths equal and find the distance:

let x be the distance of equal field strength from M

GM/x2 = 4GM/(d-x)2
4x2 = (d-x)2
4x2 = d2 -2xd +x2
3x2 + 2xd - d2 = 0
d = 1/3, d = -1 (using quadratic formula)

but d > 0, so d = 1/3 only

the distance is d/3 from the planet of mass M

so the answer is y/d = 1/3
Cheers i understand it now thanks.
6. (Original post by Charlie1523)
Thanks Does this formula apply for all situations regardless of the time difference between oscillations?
Yep I believe so
7. (Original post by spanisholive)
Sure, here it is Question 6 btw
I've asked a friend and we both got the same answer (from P to Q). I dont know what the hell this Mark shcme is saying. The field doesnt even go in that direction
8. Does anyone know why last year's grade boundaries were so low? 59/75 was 120/120 UMS.
9. (Original post by Yo12345)

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moving perpendicular to a field uses no work as its an equipotential line however moving in any other direction uses work i believe.
10. (Original post by veldt127)
Does anyone know why last year's grade boundaries were so low? 59/75 was 120/120 UMS.
I really have no idea. Maybe a lot of students didnt do as well. Hopoefully it's like that for us!!!
11. (Original post by SirRaza97)
I really have no idea. Maybe a lot of students didnt do as well. Hopoefully it's like that for us!!!
I hope so, we have to do Medical as our option unit, my only hope for an A* is a strong mark in Unit 4
12. Is everyone doing Section B first?
13. (Original post by veldt127)
Does anyone know why last year's grade boundaries were so low? 59/75 was 120/120 UMS.
There was a printing error in one of the questions; the capacitor one.
14. (Original post by SirRaza97)
I've asked a friend and we both got the same answer (from P to Q). I dont know what the hell this Mark shcme is saying. The field doesnt even go in that direction
Yeah I don't really understand it either Is it P to Q or Q to P? I thought it would've been Q to P using the left hand rule?
15. (Original post by particlestudent)
Is everyone doing Section B first?
yup
16. Are we meant to round numbers for further calculations? I tend to use exact values but often get a different answer from the mark scheme but I just assumed it's better to keep the accuracy.

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17. (Original post by Nikulp68)
There was a printing error in one of the questions; the capacitor one.
That makes sense, damn, looks like an A* might be out of reach. Thanks for explaining +1
18. (Original post by spanisholive)
Yeah I don't really understand it either Is it P to Q or Q to P? I thought it would've been Q to P using the left hand rule?
Sorry Q to P is right.
19. (Original post by alevelstresss)
yup
I honestly don't know which one to do first...
20. Typically I will take a look at Section B and see how hard it looks. Lol.

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