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# OCR A - AS - How did you do? watch

80% A
70% B
60% C etc
2. Just a quick question that occured. You know the question on forces and motion with the girl on a rope swing, her weight was 500N and there were two tension forces acting along the rope in opposite direcions. How did people solve that to find the tension?
I got into simultaneous equations with trigonometry to start off with but then i tried Sine rule, but i'm still not sure if it came out right. Any other ideas?
3. (Original post by g33k b0y)
Just a quick question that occured. You know the question on forces and motion with the girl on a rope swing, her weight was 500N and there were two tension forces acting along the rope in opposite direcions. How did people solve that to find the tension?
I got into simultaneous equations with trigonometry to start off with but then i tried Sine rule, but i'm still not sure if it came out right. Any other ideas?
I resolved forces vertically and horizontally, since the girl was in equilibrium and for equilibrium, sum of forces = zero in any direction. Then I eliminated 1 tension to calculate 1 of the tensions and then used one of my equations to find the other tension. I checked my values and they worked nicely.

Why anyone would want to answer a question like that using a vector triangle, anyone knows.
4. I know what you mean, using scale drawing isnt exactly the best way to solve tht :s I tried that first off and couldn't figure out how to solve the equation. When i used Sine rule my verticle components canceled out the 500 acting downwards so i'm hopin its ok!
5. Electrons and photons and the wave papers were brilliant. but now i realise i missed out drawing the field lines on the solenoid but i cant do anything bout it now
cant believe the first questions on both the papers though, what is the speed of the electromagnetic waves and identifying the normal!!!
6. i nearly missed out that question i think a lot of people did because it was well placed. i forgot to ask what did everyone say about the ammeter reading of the wire when temperature increased.
7. (Original post by Asian cutie)
i nearly missed out that question i think a lot of people did because it was well placed. i forgot to ask what did everyone say about the ammeter reading of the wire when temperature increased.
I said the ammeter reading won't change , only the voltmetre p.d. Theres so many random questions that I can never be to sure of which is why my optomistic about getting an A.
8. i said that to i said it would increase. well i think thats what i said
9. i said would increase as well, so i hope it's right
how did you answerthe last question about how many photons arriving per second?
just because i just did power/energy to get it
10. i cant remember but i got 2.08 (or sumfin) to 10^15.
11. (Original post by Asian cutie)
i cant remember but i got 2.08 (or sumfin) to 10^15.
yep, that's what I got. Definitely to the power of 15.
12. I said the ammeter reading would decrease because as the wire heats up its resistance increases due to more collisions of electrons with vibrating atoms in the wire, since I = V/R and the voltage supplied remains constant I must decrease as resistance increases.

And that was like 4 marks I hope it's right
13. i know there was so many ways to reason out that question i was gettin really confused in the exam.
14. Yay I got the same number of photons too

At least that's one in the bag for us all
15. 4marks I probably lost 2 but, atleast I know for definite that resistance would have increased so thats the other two saved.

How did you all do on touch sensor circuit?
The first part was a given but the second part calculating resistance i think it was. I did the everything I could got quite a big answer.
16. (Original post by mala2k)
I did the everything I could got quite a big answer.
i think i got 240 kohms or somethink along those lines
17. (Original post by Asian cutie)
i cant remember but i got 2.08 (or sumfin) to 10^15.
good, thats what i got. at least there's one mark for us and i might get one for the first question - 3 x 10^8 ms^-1
18. (Original post by katykt77)
good, thats what i got. at least there's one mark for us and i might get one for the first question - 3 x 10^8 ms^-1
lol im sur ul get more then the 3 marks uve predicted yourself. for the ratio did u get 5? i was really confused about that question
19. The last question on forces was tricky as hell, I knew velocity=gradient. But I had to think hard where to draw the tangent and what values to take.

I am glad they chose to put crap about string constant instead of Young modulus. Does any remember what the answer to the car fueling question was. It was like first time i came accross somthing like that, I just put more petrol means more mass and therefore a=f/m so acceleration would be smaller.

I really messed up on last part of AB race, How did everyone get Bs acceleration with u=80 v=80 s=120 I think. I calculated everything perfect for A but just couldnt sort out my B. a=80-80/t a=80²-80²/240
the one equation i maaged to get was just 120=80t+ ½at² couldnt find another equation with acceleration to solve it with.
20. yeh, i got 5.
i worked out the current through the bulb, then worked out the current for the 20ohms.
it was 3/0.6

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