Hey there! Sign in to join this conversationNew here? Join for free
x Turn on thread page Beta
 You are Here: Home >< Physics

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

1. 6 marker:

Talking about circular motion in the context of the mass on a string.
V is changing but speed is constant - dirrection always changing therefore accelerates
Force (centripetal) acts perpendicular to direction of motion - conditions for u.c.m
Centriptal force provided by cent acc
tension in string acts as centr - force

difficult to demonstarte horizontally:
theres mass which is acted on by gravity thus downward component makes it harder to veer perfectly horizontal,
measuring this accuracy is a hard thing to do practically

anything I may have missed?
2. (Original post by AR_95)
YES MAN FINALLY A QUESTION I ACTUALLY GOT RIGHT LOOOOOOL

i was stuck on this one for 20 minutes. Was kicking myself because I had done it before in a past paper!!!
lol 20 minutes for 1 mark, what a bargain

Just hoping the grade boundaries don't change significantly
3. (Original post by Mehrdad jafari)
We literally had thousand hours of discussion about such a question

Posted from TSR Mobile
I came and got involved at the wrong time then ))))))
4. Well I felt okay about that paper until I realised the mistakes I'd made:

• Didn't half the 4.4x10^10 electrons
• Said there was no effect on damping
• Said steel was to reduce power losses
• Messed up the question on coils P and Q.

Ffs.

Posted from TSR Mobile
5. (Original post by Amanzz)
That's true, I was illustrating that stokes' law depends on velocity, which doesn't change what a new mass is added provided that there isn't a large change in surface area.

Posted from TSR Mobile
That analysis wouldn't necessarily apply because "radius" isn't well-defined for non-spherical objects, so the variables involved could be different altogether.
6. (Original post by NEWT0N)
lol 20 minutes for 1 mark, what a bargain

Just hoping the grade boundaries don't change significantly
not sure why it was so long, every other question I did fine and I finished the MC in 35 minutes ( leaving the capacitor one for the end)
7. (Original post by CD223)
Well I felt okay about that paper until I realised the mistakes I'd made:
• Said there was no effect on damping

I also said there was no effect on damping but how is that wrong? Surely the surface area is a key factor in determining damping.
As surface area remains the same damping isn't affected by the ring.

I could be wrong though.
8. (Original post by CD223)
Well I felt okay about that paper until I realised the mistakes I'd made:

• Didn't half the 4.4x10^10 electrons
• Said there was no effect on damping
• Said steel was to reduce power losses
• Messed up the question on coils P and Q.

Ffs.
Posted from TSR Mobile
Why do the electrons halve? Can't quite remember the question but I know I didn't!
9. i think it was easier to lose marks this year than last years, very awkward wordy questions and a lot of tricks. I think grade boundaries may drop slightly ie a mark or 2
10. (Original post by CD223)
Well I felt okay about that paper until I realised the mistakes I'd made:

Didn't half the 4.4x10^10 electrons
• Said there was no effect on damping
Said steel was to reduce power losses
• Messed up the question on coils P and Q.

Ffs.

Posted from TSR Mobile
I did those as well (the ones in bold)

Chin up, I'm sure you'll be fine. If that's really the total number of mistakes you made you're still looking at a high (full UMS even?) A*. I'm hoping for either just scraping full UMS but hopefully an A* in any case, although the fact that there are like 5 marks between each grade is slightly worrying
11. (Original post by CD223)
Well I felt okay about that paper until I realised the mistakes I'd made:

• Didn't half the 4.4x10^10 electrons
• Said there was no effect on damping
• Said steel was to reduce power losses
• Messed up the question on coils P and Q.

Ffs.

Posted from TSR Mobile
It's all cool man. I'm sure i made more mistakes than you did but I'm very happy with the exam. For me making mistakes is not a problem, but not learning anything from them is a problem.

Posted from TSR Mobile
12. (Original post by QueNNch)
I also said there was no effect on damping but how is that wrong? Surely the surface area is a key factor in determining damping.
As surface area remains the same damping isn't affected by the ring.

I could be wrong though.
It also relies on momentum
13. (Original post by Lau14)
I haven't heard anyone else notice this yet, but it would be bad if they had messed up!
It was mentioned a lot earlier up the thread!
14. (Original post by Lau14)
Why do the electrons halve? Can't quite remember the question but I know I didn't!
The question asked for the number of electrons on the NEGATIVE plate ONLY.

As each capacitor plate shares equal number of electrons it is halved.
15. (Original post by Chazley123)
6 marker:

Talking about circular motion in the context of the mass on a string.
V is changing but speed is constant - dirrection always changing therefore accelerates
Force (centripetal) acts perpendicular to direction of motion - conditions for u.c.m
Centriptal force provided by cent acc
tension in string acts as centr - force

difficult to demonstarte horizontally:
theres mass which is acted on by gravity thus downward component makes it harder to veer perfectly horizontal,
measuring this accuracy is a hard thing to do practically

anything I may have missed?
I reckon you will get 4/6. I wrote similar but my teacher said you had to state that the tension in the string resolved vertically TSin(x) would be equal to mg if it is to remain horizontal. Also explain the 3 laws in context
16. (Original post by QueNNch)
Your argument is valid but I've also done Q 20 in past papers and it's definitely -322

Change in direction of current, making force apply in opposite direction. (Flemings LHR)
I know i've just looked, it's where the initial reading was zeroed, therefor it can have a negative value as mass already acts on the scales
17. (Original post by Chazley123)
6 marker:

Talking about circular motion in the context of the mass on a string.
V is changing but speed is constant - dirrection always changing therefore accelerates
Force (centripetal) acts perpendicular to direction of motion - conditions for u.c.m
Centriptal force provided by cent acc
tension in string acts as centr - force

difficult to demonstarte horizontally:
theres mass which is acted on by gravity thus downward component makes it harder to veer perfectly horizontal,
measuring this accuracy is a hard thing to do practically

anything I may have missed?
You do realize it is impossible to do it perfectly horizontally... not harder.

BECAUSE: there is no vertical component of the tension to counter act the weight of the ball.
18. (Original post by Sonnyjimisgod)
I reckon you will get 4/6. I wrote similar but my teacher said you had to state that the tension in the string resolved vertically TSin(x) would be equal to mg if it is to remain horizontal. Also explain the 3 laws in context
examiners forever wanting you to go further :/
19. (Original post by AR_95)
not sure why it was so long, every other question I did fine and I finished the MC in 35 minutes ( leaving the capacitor one for the end)
Nice, I think I did exactly 45 minutes on MC or slightly lower but I remember making some mistakes while filling the answer sheet which cost me a few minutes to fully check through and re-check (the last thing you want is to fill out the answer sheet wrong!)
20. (Original post by chizz1889)
It also relies on momentum
The alternative answer which would oppose my thoughts is that if it has a greater mass it has more mgh and then it has a greater 1/2mv² and so there is a greater drag force. I thought the damping force was only because of drag on a pendulum, so I really don't know which solution is correct.

Posted from TSR Mobile

Reply
Submit reply
Turn on thread page Beta
TSR Support Team

We have a brilliant team of more than 60 Support Team members looking after discussions on The Student Room, helping to make it a fun, safe and useful place to hang out.

This forum is supported by:
Updated: February 22, 2016
Today on TSR

### I've studied the wrong subject

...Should I go back to school?

Poll
Useful resources

## Make your revision easier

Can you help? Study help unanswered threadsStudy Help rules and posting guidelinesLaTex guide for writing equations on TSR

## Groups associated with this forum:

View associated groups

The Student Room, Get Revising and Marked by Teachers are trading names of The Student Room Group Ltd.

Register Number: 04666380 (England and Wales), VAT No. 806 8067 22 Registered Office: International House, Queens Road, Brighton, BN1 3XE

Write a reply...
Reply
Hide
Reputation gems: You get these gems as you gain rep from other members for making good contributions and giving helpful advice.