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

1. (Original post by AnneOldman)
Does anyone know any examples of the different types of damping?

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For a basic pendulum the easiest thing is putting a piece of card in the oscillation path.

For a bridge changing the design, adding more supports, stopping people walking on it and things such a soldiers have to break step

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2. (Original post by utvctang)
Attachment 424655 Stuck with these two..

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Firstly its not rotating its just the flux that is changing so EMF= d/dt (BA) * n
Since the increase is uniform and the time take is t EMF= BAN/t
Take N and T to the other side and you get EMF*T/N = Flux
3. (Original post by frankiejayx)
Okay thanks, on a question it had two positives with a point X of 0 potential in between, but im guessing one of the charges were meant to be negative!
Oh! Could you post the question?

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4. (Original post by Leonacatherine)
Can anyone explain ehat they mean by E in the june 14 six marker
I get the rest but dont get wat theyre referring to by E
http://filestore.aqa.org.uk/subjects...W-MS-JUN14.PDF
http://filestore.aqa.org.uk/subjects...2-QP-JUN14.PDF
The EMF.

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5. (Original post by _Caz_)
could someone help me understand why gravitational/electric field strength is vector please?
They're respectively defined as the force per unit mass/charge exerted on a test mass in the field.

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6. could someone explain this question please? I've seen several of these questions come up before and I just don't get them. Like why would the sides attract each other??
Attached Images

7. (Original post by _Caz_)
could someone help me understand why gravitational/electric field strength is vector please?
Because they have direction gravity is always acting towards the centre of the body same with radial electric. In a uniform field the dorection is positive to negative.
8. (Original post by utvctang)
Attachment 424655 Stuck with these two..

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For the second consider the area swept per second, so the area= 60*150
A= 9000
EMF= BAN, only a single coil
EMF= 9000* B
0.09V
9. (Original post by aprocrastinator)
could someone explain this question please? I've seen several of these questions come up before and I just don't get them. Like why would the sides attract each other??
PQ and RS is where current (therefore charges) is parallel to magnetic field lines so no force is experienced on them

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10. (Original post by JaySP)
Because they have direction gravity is always acting towards the centre of the body same with radial electric. In a uniform field the dorection is positive to negative.

thank you !
11. Im all set for the MC, but not prepared at all for any 6 markers..
12. (Original post by DanielWall96)
Firstly its not rotating its just the flux that is changing so EMF= d/dt (BA) * n
Since the increase is uniform and the time take is t EMF= BAN/t
Take N and T to the other side and you get EMF*T/N = Flux
(Original post by DanielWall96)
For the second consider the area swept per second, so the area= 60*150
A= 9000
EMF= BAN, only a single coil
EMF= 9000* B
0.09V
Thanks a bunch!
13. (Original post by AR_95)
Im all set for the MC, but not prepared at all for any 6 markers..
You'll be okay! I'm scared for multiple choice.. they just mess us up sometimes. -_-

6 marks will be something from the past papers or something totally new..
14. Question 1c) june 2013 phya4/2 ? Help much appreciated as I never know how to do these

http://filestore.aqa.org.uk/subjects...2-QP-JUN13.PDF
15. (Original post by aprocrastinator)
could someone explain this question please? I've seen several of these questions come up before and I just don't get them. Like why would the sides attract each other??
is the answer B, because the currents are parallel to the field
16. (Original post by CD223)
They're respectively defined as the force per unit mass/charge exerted on a test mass in the field.

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ahh okay - thank you!
17. (Original post by _Caz_)
No AQA for me. was a terrible paper. pretty sure about 8 marks of it were not even on the specification...
Ah that sucks. Ours was absolutely horrific as well, fingers crossed for really low boundaries.

(Original post by Mattniemier)
Is anyone else revising from the CGP guide rather than the nelson thornes book
You can use it alongside classnotes, but if you mean the revision guide it doesn't actually have everything in so be aware of this!
18. (Original post by CD223)
PQ and RS is where current (therefore charges) is parallel to magnetic field lines so no force is experienced on them

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Thank you I really hope I don't make stupid mistakes in this paper I need to get as high as UMS as possible!
19. (Original post by aprocrastinator)
could someone explain this question please? I've seen several of these questions come up before and I just don't get them. Like why would the sides attract each other??
If you don't mind me asking, what year paper is this question from?
Question 1c) june 2013 phya4/2 ? Help much appreciated as I never know how to do these

http://filestore.aqa.org.uk/subjects...2-QP-JUN13.PDF
Lowest common multiple which is 38s. After each oscillation of the 2s pendulum the 1.9s pendulum become 0.10s more out of phase. So after 20 cycles, the phase difference between the 2s pendulum and the 1.9s pendulum becomes 2s. As this is equal to the 2s pendulum's time period, they are back in phase (in the same way that for any waveform 2pi out of phase is the same as being in phase)

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