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# AQA Physics Unit 2 - Unofficial Markscheme

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1. (Original post by SunnyBoys)
Just that it could not explain at all why ratios got me the answer, as I didn't even know that the ratios got me the correct answer in the first place. I originally attempted to use current but current changes in the series circuit as the resistance changes so it couldn't be used. How could I have explained something I didn't even understand lol
I think you almost cracked it! To overcome the problem of the current changing and causing a heating effect, i just selected one value (e.g. 200 ohms) and then used the graph to find that the voltage across V1 and v2 were 9 and 3. Hence, I calcualted the current across the varibale reistor and then subbed it in, to find the resistance of thefixed resistor - since here i only used one reistance for the variable resistor, heating effect would be negligible. Though, for two marks, I felt it was more of those physics "challenge" questions, perhaps there was another way to explain it using ratios or something a lot quicker tho.
2. You know the question about the materials of the plug? Did you have to why or was it just a 2 marker. I'm worried now because I never said why but I was almost sure it was just for 2 marks 😐
3. For the question about the materials of the plug, did you definitely have to say why? I was almost sure it was only a 2 mark question and now im worried :/
4. (Original post by BDunlop)
We have eleme to heavier than iron on earth which could have only been formed during a super nova explosion thus there must have been a supernova
Yeah I wrote that aswell, just trying to fill in any missing questions on OP's mark scheme
5. Doesn't this seem a little complicated for a 2 marker? There's one mark for stating the correct resistance and one for explaining, it should be a simple explanation surely?
6. yes you had to write why
7. What do you guys think 30/60 marks will be?
8. (Original post by MaxHSloan)
For the question about the materials of the plug, did you definitely have to say why? I was almost sure it was only a 2 mark question and now im worried :/
you had to write why aswell
9. (Original post by Anygy)
What do you guys think 30/60 marks will be?
More than likely a B
10. (Original post by 1jonam16)
oh fair enough, do you htink that if i write my answer to one question in the answer lines and then continue my answer into answer lines below for a different quuestion, but obviously use arrows to indicate i have done so, it will be marked?
it depends tho because they are scanned in to a computer and the Q's are sent off to different markers separately, but it probs will get marked
11. For the last acceleration question i got 12 m/s^2 and quite a lot of people on reddit seem to agree. Could be either, im just putting it out there
12. for the precautions for working in a nuclear plant i said that they should have a geiger counter in the room an if it begins to beep faster they will leave the room asap will i get a mark?
13. thanks for everyone helping me fill it in
has anyone got any ideas what the questions with the answer of 0.015A is?
14. the resistor one should be 200ohms as fixed resistance value will increase due to the heating effect of the current
hence it will only go to 600ohms after a while but must have started initially at 200ohms
15. what would the grade boundary be like? Would it be lower than last year?
16. (Original post by trollface54)
the resistor one should be 200ohms as fixed resistance value will increase due to the heating effect of the current
hence it will only go to 600ohms after a while but must have started initially at 200ohms
No it has a fixed value as stated in the question. It started 600 ohms, I calculated it using ratio and it was 600 ohms throughout the entire graph
17. (Original post by SunnyBoys)
No it has a fixed value as stated in the question. It started 600 ohms, I calculated it using ratio and it was 600 ohms throughout the entire graph
I said 600 ohms and for the explanation i said because that's where both voltmeters level off... Would i get the mark?
18. (Original post by CopyThat)
I said 600 ohms and for the explanation i said because that's where both voltmeters level off... Would i get the mark?
I think that's was how you were meant to calculate it, I'm not sure but I think you will
19. (Original post by CopyThat)
I said 600 ohms and for the explanation i said because that's where both voltmeters level off... Would i get the mark?
AHHHH THAT MAKES Sense - i think that's how you're meant to do it. Do you think I'll get the mark for doing 3 calculations instead? I sitll got 600 ohms.

(Original post by hannahb9184)
it depends tho because they are scanned in to a computer and the Q's are sent off to different markers separately, but it probs will get marked
Also, aren't individual questions sent to examiners? E.g. question 1, 2,3 rather than part a,b,c? Because otherwise there'd be too much hassle. Anyays thank you,
20. (Original post by Akila1)
84kg
22m/s2
0.015A
22m/s^2 isnt the answer for the last question. The formual to find out acceleration is resultant force/mass. And in the question it said the upthrust force was 1850N, but that dosent mean that it is the overall force acting on the object. You'd have to also take account in the force going the opposite direction which is the weight of the person and the jetpack which is 840N. You then fidn the resultant force by doing 1850-840 which is 1010N. So the resultant force of the object is 1010N. You then do 1010/84 which is the mass of the jetpack and the person which igves you an answer of 12 m/s^2. Hope you understand how 12 is the answer not 22 .

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