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

1. (Original post by shuu00)
Omg was N the mass of the original nucleus or the daughter nucleus?
Daughter
2. What was the time taken for V to decrease to 0.2Vo?

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3. (Original post by Mango Milkshake)
Daughter
Well ****. Thats 6 marks out the window lol.
4. (Original post by Rid123)
Paper was pretty standard, six marker was nice comparmed with past papers,
Question one calculations i got
8.3mF
3.7×10^-5 j
36s
77000ohms

216 nuleons
V=mv/N
Limitation small angle approximation?
I got 8.1 μF

Can't remember the rest uh
5. (Original post by Rid123)
I put advan is the EM brakes wont wear down as much as the other ones with the pads
And dis EM brakes nore expensive?? Idk i dont think got either of them ahaha
I put the same theres no friction as moving parts not in contact so less wear and EM must be more expensive and theres the cost of all that electricity too
6. What was the unit - I worked it out to be C^2 kg^(-2)?
8. Disadvantage for EM brakes - if your electrical system fails in your car, you won't be able to brake
9. (Original post by Beautywithabrain)
Oh sh*t! Praying for low grade boundaries now
It was 28 seconds
10. (Original post by kingaaran)
What was the unit - I worked it out to be C^2 kg^(-2)?
Yup
11. can anyone put up how they did the momentum of alpha question? i couldn't do it but i wanna see if i got any of the method marks
12. (Original post by duncant)
got this but I got RC=28s? 45/-ln(0.2)
I think I did the same as you did but I only got 28 seconds after rounding my answer up.
13. (Original post by rich1334)
Disadvantage for EM brakes - if your electrical system fails in your car, you won't be able to brake
I wrote car takes longer to stop. No idea if its right
14. Would saying that the constant magnetisation and demagnetisation of the electromagnet would waste energy be a valid disadvantage?

Also, I accidentally put T^2 on the x axis and l on the y axis in the 6 marker - how many marks would I lose for that?
A B B D B C D A B C B A C A C A B A C A A D C B D
16. (Original post by exmerelda)
can anyone put up how they did the momentum of alpha question? i couldn't do it but i wanna see if i got any of the method marks
(Original post by exmerelda)
can anyone put up how they did the momentum of alpha question? i couldn't do it but i wanna see if i got any of the method marks
use the equation they give yiu in the previous part to work out the kinetic energy of alpha, work out speed, times by mass to give momentum
17. (Original post by 09aghandhi)
spent every bloody holiday in the library, revised for hours, and except 6 marker this was **** for me. Even worse, apparently im the only person who found it hard, so high boundaries. a D if i'm lucky. I'll just take a gap year, then try get into an apprenticeship. AAB required for surry, physics won't be more than a C after this.
i feel u bro.... ive tried so flipping hard all year but after that i'll be surprised if i got a D
18. (Original post by Rid123)
I put advan is the EM brakes wont wear down as much as the other ones with the pads
And dis EM brakes nore expensive?? Idk i dont think got either of them ahaha
I put slow down quicker with stronger magnets
Disadv was may not work in wet conditions

Prob bs but thats what i put
19. Had an absolute mare for this and completely missed out the final question, for some reason thought it was the end of the paper after the 6 marker question up to the 4g one. Can anyone tell me how many marks question 5 was out of?

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