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

1. (Original post by Its Andy)
That capacitor question annoyed me so much. I was internally raging. I worked out that the current dips 1/400 of a square.

It still annoys me now. Here's a graph of a capacitor discharging, what happens when we times the resistance by 2000?

Now try and draw that on the same axis.
B******s
Yeah what we're aqa playing at! Did they mean 150kohms? My graph was so small
2. Well that could've gone worse!
3. Damping decreased with ring. T=2πxsqrt(m/k) with larger mass gives longer time for same oscillation so lower velocity. Lower velocity reduces effect of the damping force air resistance.
4. My first answers on MC were:

ABCDBBCC

Can't remember the sequence after that

(Original post by Fred Cantoni)
Any one else get A A A as the first three MC?

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5. I put no change in dampening?
No change to surface area and no shm pendulum equations depend on mass at all?
6. (Original post by Ilovemaths96)
number of rotations i got 2????
Yes.

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7. (Original post by king cobra)
Did people get 1.4 for the height ?

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Yay!

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8. Whoever did the specimen paper I posted the link for last night, how happy were you with the first question!!!
9. Got over 1m for length of string!??
10. (Original post by Cmog)
If they've made a typo that impacts it that much, they may even scrap those marks
I hope so. The worst bit is I spent so long going back over that question, trying to see if I was wrong, I didn't get to check through any of my other answers. But never mind, may as well focus on the next exam now.
11. (Original post by 000alex)
I put no change in dampening?
No change to surface area and no shm pendulum equations depend on mass at all?
I think you can argue either way!
12. Anyone else get 131 degrees for question 5a?
13. (Original post by F13ND)
Damping decreased with ring. T=2πxsqrt(m/k) with larger mass gives longer time for same oscillation so lower velocity. Lower velocity reduces effect of the damping force air resistance.
No it wasn't spring
14. (Original post by F13ND)
Damping decreased with ring. T=2πxsqrt(m/k) with larger mass gives longer time for same oscillation so lower velocity. Lower velocity reduces effect of the damping force air resistance.
But it wasn't a mass spring system was it?! I put that reason but crossed it out as I realised it's for a simple pendulum so mass doesn't even matter as it's just T=2pi root l/g
15. (Original post by Willow1.21)
I hope so. The worst bit is I spent so long going back over that question, trying to see if I was wrong, I didn't get to check through any of my other answers. But never mind, may as well focus on the next exam now.
I hate capacitors so drew a line and went yeah ok
16. (Original post by F13ND)
Damping decreased with ring. T=2πxsqrt(m/k) with larger mass gives longer time for same oscillation so lower velocity. Lower velocity reduces effect of the damping force air resistance.
That's the equation for mass spring system??
17. (Original post by jf1994)
Anyone else get 131 degrees for question 5a?
Yes!! You have no idea how great it feels when even one person gets the same answer as you, I had no clue what I was doing just kept plugging numbers in! Did you get 2 revolutions per second as well?
18. What did you put for the last MC question about the steel core?
19. (Original post by Sbarron)
No it wasn't spring
Doesn't damping result in increased time anyway? I said m doesn't affect t and damping would require t to decrease??
20. (Original post by Cmog)
Was it steeper gradient with less area under graph, I forgot to adjust my current
I did a less steep graph because I thought with greater time constant it would discharge at a slower rate :/

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