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

1. Here are my multiple choice answers, let me know which you agree with
1,D
2,D
3,B
4,D
5,B
6,C
7,D
8,B
9,C
10,C
11,C
12,A
13,C
14,A
15,C
16,A
17,B
18,D
19,D
20,A
21,A
22,D
23,C
24,B
25,D
2. anyone get the multiple choice q?
3. what do people think the grade boundaries will be. some are saying its high but i think it will be lower or the same as last years (54 for an a*) i cant see how it will be higher
4. i ticked the third box (cant remember what the question was tho) is that right????
5. does anyone know why we had to write all details and hand in our multiple choice question papers?
6. Can someone explain why V is not = -mv/N surely mv=-NV so -V=mv/n so V=-mv/N?
7. what is the answer about the beta - thing. i said a proton is created by neutron and electron is released, the recoil speed is negligble because neutron turn into proton
8. Will 45 marks get me a B , please tell me someone
9. for the graph i ****ed that q up but will i get a mark for saying that the g is 9.81 on the earth like marking it on the y axis
10. (Original post by CourtlyCanter)
I said 4F and X to Y
I said 2F i think from X to Y
11. For anyone still wondering, the velocity of the recoiling nucleus was V, in the opposite direction to the alpha particle. The magnitude of the recoiling nucleus velocity was V but the velocity, taking right being positive, is -V. Therefore, 0=mv-NV and V=mv/N
12. (Original post by dirtydawg5)
Can someone explain why V is not = -mv/N surely mv=-NV so -V=mv/n so V=-mv/N?
0=mv - NV
adding NV to each side gives NV = mv
13. (Original post by marioman)
No, once you reach the 120 UMS boundary then you can get no more UMS from that paper.
That's a relief. Would've got 72/73 assuming all MC correct but the blank page before the last question threw me, only realised there was an extra question with a minute left..
14. surely someone has the questions or a copy of the multiple choice
15. (Original post by dirtydawg5)
Can someone explain why V is not = -mv/N surely mv=-NV so -V=mv/n so V=-mv/N?
By my understanding, V and v are not velocities themselves. They are the magnitude of the velocity. It is only the velocity once the direction of the arrow is taken account of. The two arrows were in opposite directions hence the velocities were -V and v (or V and -v depending on whether you take right or left as positive). So NV - mv = 0 ==> V = mv/N.
16. does anyone have the questions themselves along with the answers to the multpile q because letters aint really helping me in determining my mark
17. (Original post by Jordenwilder1998)
what is the answer about the beta - thing. i said a proton is created by neutron and electron is released, the recoil speed is negligble because neutron turn into proton
Hmm, I said force of electrostatic attraction between beta particle and nucleus would affect momenta and final velocities.
18. (Original post by johnthedog)
For anyone still wondering, the velocity of the recoiling nucleus was V, in the opposite direction to the alpha particle. The magnitude of the recoiling nucleus velocity was V but the velocity, taking right being positive, is -V. Therefore, 0=mv-NV and V=mv/N
The question gave velocity, not speed. Therefore the direction is already taken into account with the velocity.

So it was definitely -mv/N
19. (Original post by dirtydawg5)
Can someone explain why V is not = -mv/N surely mv=-NV so -V=mv/n so V=-mv/N?
20. (Original post by Questioner1234)
momentum before is 0

mv-MV=0
mv=MV
V=mv/M
For an explosion mv+MV=0 not mv-MV?

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