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

1. (Original post by Zeus579)
For two reasons I wrote:
Heat loss due to resistance of the wire
Work done against air resistance due to motion of the mass.
I said energy lost due to the heating effect of the current, does that count?
2. (Original post by AR_95)
I said energy lost due to the heating effect of the current, does that count?
I'm not sure
3. I notice one of the answeres was 0.06 something and I left it to 6. something to 10^-2, will I still get the mark?
4. (Original post by AR_95)
I notice one of the answeres was 0.06 something and I left it to 6. something to 10^-2, will I still get the mark?
I did that too it's fine.

I think it was something 0.0603 and I wrote it as 6.0 * 10^-2
5. Hey, for the electric field strength I put Q as 60nC rather than 30nC (as 60 sas used for work done) would I get any marks for using that value?
6. (Original post by RemainSilent)
Hey, for the electric field strength I put Q as 60nC rather than 30nC (as 60 sas used for work done) would I get any marks for using that value?
I think you would get one mark out of 2 if this is not a wishful thinking

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7. Hey I haven been on this thread in a while, you for the question about the ring you said the answer was

(1) Cone with ring shows less damping.
3 marks from:
Damping reduces the amplitude of oscillations/total energy of system (over time) (1)

Air resistance is same for both (the cone with and without ring) (1)

Reducing speed reduces kinetic energy (and therefore total energy) of cone (and therefore amplitude of oscillations) (1)

I thought the answer would be no effect because the pendulum is accelerating due to gravity, so its acceleration is not dependent on mass
acceleration is proportional to displacement so if its acceleration is unaffected by mass then surely the amplitude (maximum displacement) wouldnt be either and in that case the ring would have no effect on damping?
8. (Original post by Leonacatherine)
Hey I haven been on this thread in a while, you for the question about the ring you said the answer was

(1) Cone with ring shows less damping.
3 marks from:
Damping reduces the amplitude of oscillations/total energy of system (over time) (1)

Air resistance is same for both (the cone with and without ring) (1)

Reducing speed reduces kinetic energy (and therefore total energy) of cone (and therefore amplitude of oscillations) (1)

I thought the answer would be no effect because the pendulum is accelerating due to gravity, so its acceleration is not dependent on mass
acceleration is proportional to displacement so if its acceleration is unaffected by mass then surely the amplitude (maximum displacement) wouldnt be either and in that case the ring would have no effect on damping?
This is what I also put - I had the same thought process as you on this one!
To be honest, people are making good points for both accounts... I assume the other answer is correct, only because a bulk of people came up with the same response. However, that doesn't mean it's right. Regardless, you should still get marks for your explanation of your reasoning. Well I hope we do :P
9. (Original post by moontheloon)
This is what I also put - I had the same thought process as you on this one!
To be honest, people are making good points for both accounts... I assume the other answer is correct, only because a bulk of people came up with the same response. However, that doesn't mean it's right. Regardless, you should still get marks for your explanation of your reasoning. Well I hope we do :P
I put no effect due to time period not depending on mass and the fact there was no increase in surface area therefore no change in damping is observed.

I only put the other explanation on the mark scheme due to the bulk of people disagreeing with my reasoning haha.

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10. (Original post by moontheloon)
This is what I also put - I had the same thought process as you on this one!
To be honest, people are making good points for both accounts... I assume the other answer is correct, only because a bulk of people came up with the same response. However, that doesn't mean it's right. Regardless, you should still get marks for your explanation of your reasoning. Well I hope we do :P
If I'm honest I don't actually understand the answer they put up? I feel like it's just a description of what damping is and how damping reduces amplitude and hasn't actually been applied to the question ?

Maybe there were better explanations I haven't seem them. I'm pretty sure we're right on this one. Until someone proves me wrong I'll keep thinking it too haha!
11. (Original post by CD223)
I put no effect due to time period not depending on mass and the fact there was no increase in surface area therefore no change in damping is observed.

I only put the other explanation on the mark scheme due to the bulk of people disagreeing with my reasoning haha.

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I cant see any physical reasoning as to how it could increase or reduce damping at all? I'm really suprised there were so many people that thought it would?

This was a simple harmonics question we've had a year of people drumming that the amplitude is proportional to acceleration, it was accellerating due to gravity ? so how can the mass of the ring have any effect on the system?

Haha sorry i know youre agreeing with me, i wouldnt mind if I could understand the reasoning of the other side but i genuinely dont see it

Oh well i guess its all done now

hoping we are right
12. (Original post by Leonacatherine)
I cant see any physical reasoning as to how it could increase or reduce damping at all? I'm really suprised there were so many people that thought it would?

This was a simple harmonics question we've had a year of people drumming that the amplitude is proportional to acceleration, it was accellerating due to gravity ? so how can the mass of the ring have any effect on the system?

Haha sorry i know youre agreeing with me, i wouldnt mind if I could understand the reasoning of the other side but i genuinely dont see it

Oh well i guess its all done now

hoping we are right
we are the "few"
13. (Original post by Leonacatherine)
I cant see any physical reasoning as to how it could increase or reduce damping at all? I'm really suprised there were so many people that thought it would?

This was a simple harmonics question we've had a year of people drumming that the amplitude is proportional to acceleration, it was accellerating due to gravity ? so how can the mass of the ring have any effect on the system?

Haha sorry i know youre agreeing with me, i wouldnt mind if I could understand the reasoning of the other side but i genuinely dont see it

Oh well i guess its all done now

hoping we are right
(Original post by moontheloon)
we are the "few"

It's not just accelerating with gravity, it has an acceleration that goes from +max to 0 to -max. remember that there is an acceleration towards the equilibrium point, and it is opposite to the direction. If the mass increased, the restoring force or acceleration must have also increased so I think more work is done to return the swing towards equillibrium point. That's why I think with the ring on damping is increased now

But in the exam, I said no effect for similar reasons to you guys
14. (Original post by AR_95)
It's not just accelerating with gravity, it has an acceleration that goes from +max to 0 to -max. remember that there is an acceleration towards the equilibrium point, and it is opposite to the direction. If the mass increased, the restoring force or acceleration must have also increased so I think more work is done to return the swing towards equillibrium point. That's why I think with the ring on damping is increased now

But in the exam, I said no effect for similar reasons to you guys
The acceleration towards the midpoint is due to gravity?
15. (Original post by AR_95)
I notice one of the answeres was 0.06 something and I left it to 6. something to 10^-2, will I still get the mark?
If significant figures are not stated in the question you usually give the answer to the amount if sig figs given in the question, though usually in the markscheme it says accept all except 1sf, so as long as do didn't put 0.1 you should be fine.
16. (Original post by Leonacatherine)
The acceleration towards the midpoint is due to gravity?
idk i got the question wrong its best I just leave it now hehe
17. (Original post by AR_95)
It's not just accelerating with gravity, it has an acceleration that goes from +max to 0 to -max. remember that there is an acceleration towards the equilibrium point, and it is opposite to the direction. If the mass increased, the restoring force or acceleration must have also increased so I think more work is done to return the swing towards equillibrium point. That's why I think with the ring on damping is increased now

But in the exam, I said no effect for similar reasons to you guys
Im pretty sure the restoring force is mg, its all about newtons laws theres only acceleration because when its not at equlibrium the forces are unbalanced and there is a resultant force. it accelerates towards equilibrium because thats where the forces are balanced
F =mg F =ma so the m's cancel out and a=g
its acceleration is due to gravity
18. (Original post by AR_95)
idk i got the question wrong its best I just leave it now hehe
Haha fair,still never know! no ones seen the mark scheme
19. Is it true this paper's mark scheme will be "released" on 21st June? I heard the "10 day rule" appears to affect some but not all exams.

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20. Hi
I have a question. Why do solar powered radios use battery indicator when they are rechargeable and do solar powered radios need to use sunlight all of the time to make sure they're powered up but why use battery indicator ?
Help would be appreciated as I need it urgently.

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