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# AQA physics UNIT 3 monday 30th jan 2012

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1. Hello Anyone what did you write for the bodes law questions????????????????
2. Ok, so doing this made me go and now I'm at a

Very hard, hoping for grade boundaries to be as low as the *something thats low*

I got 3 for the magnification and the time base was 0.000005.
3. (Original post by mazam)
I wrote 15 as well though I'm not sure if its right.

Also how did you get the answer 3.14 for the magnification?

And 0.15m for the screw question, don't you have to divide it by two. As 0.15 is the distance there and back and you want the distance to the crack.
I'm pretty sure it isn't, I'm afraid. Oh well!

Magnification was image height / object height.

Yeah, probably did actually... I do far better on the more difficult A level papers than I do on these...
4. (Original post by CaptainJim)
Ok, so doing this made me go and now I'm at a

Very hard, hoping for grade boundaries to be as low as the *something thats low*

I got 3 for the magnification and the time base was 0.000005.
Yeah, so it was 6000 x 0.0000025 = Distance there and back. So dividing this by two would have been the right answer I suppose! Unless it wanted the total distance traveled by the wave?

What were the Bode's Law questions on? I've forgotten
5. I felt that the timebase question was unfair considering they added a key of:

1cm = 0.000005, while in actuality each square was 0.5cm (measured)

Because of which I times the timebase by 2.5CM rather than 5CM and got a the answer that way.

I was thinking about going the other way but then assumed they put that there to trick people up, looks like it was the opposite to what I was thinking.

Now tell me how that has anything to do with testing our scientific ability?
6. (Original post by VY Rose)
I'm pretty sure it isn't, I'm afraid. Oh well!

Magnification was image height / object height.

Yeah, probably did actually... I do far better on the more difficult A level papers than I do on these...
What were the two numbers you divided to get 3.14?
7. (Original post by mazam)
And 0.15m for the screw question, don't you have to divide it by two. As 0.15 is the distance there and back and you want the distance to the crack.

Yep, the grade boundaries better be low
8. Bodes law I put yes because the calculations where similar to the actual distance, then the one about a planet in between mars and Jupiter at 2.8Au I said that the scientists opinion would change because the predicted distance was the same as the actual distance, the last one I didn't know i said the calculation may have been outdated and the orbits may have changed :/
9. what did you write for the transformer question about the radio? i put so it could be used at home for domestic use as the voltage is stepped down?
10. hang on though - wasnt the sound question 6000m/s so therefore you had to divide the answer by 100 to get it in cm ?
11. The voltage had to be stepped down so it didn't blow up
12. (Original post by MrLegendary)
hey guys, new here, what answer did you get for the magnification? something along the lines of 3.14 ??
I got 0.5714.............
erm
13. (Original post by sandeater)
how did you get 0.15m for the front of the screw i spent ages trying to do it but i couldn't explain?>???
I got 0.075 don't you have to divide it by 2 because it's there and back?
14. Did anyone get something like this for the ray question?

Everyone got 3.14 for the magnification apparently, am I the only one who got this and 4/7 = 0.57 for the magnification
15. (Original post by luke)
I got 0.075 don't you have to divide it by 2 because it's there and back?
16. (Original post by luke)
Did anyone get something like this for the ray question?

Everyone got 3.14 for the magnification apparently, am I the only one who got this and 4/7 = 0.57 for the magnification
No dont think thats right sorry...Firstly it said you have to only draw 2 rays, and secondly, the green ray should go through the focus on the right side and im not sure what the yellow one was... then you have to trace the rays back and a virtual larger image is formed on the left you got one ray right so hopefully youll get at least one mark for that!
17. (Original post by luke)
Did anyone get something like this for the ray question?

Everyone got 3.14 for the magnification apparently, am I the only one who got this and 4/7 = 0.57 for the magnification
I think here you got confused between a lens and a mirror. You will probably get a mark for the middle ray, and another if you remembered to put the the arrows on the rays.
18. (Original post by Zaii786)
No dont think thats right sorry...Firstly it said you have to only draw 2 rays, and secondly, the green ray should go through the focus on the right side and im not sure what the yellow one was... then you have to trace the rays back and a virtual larger image is formed on the left you got one ray right so hopefully youll get at least one mark for that!
Not forgetting that an image magnified by 0.57 would be smaller! :P
19. (Original post by Manunited_96)
Bodes law I put yes because the calculations where similar to the actual distance, then the one about a planet in between mars and Jupiter at 2.8Au I said that the scientists opinion would change because the predicted distance was the same as the actual distance, the last one I didn't know i said the calculation may have been outdated and the orbits may have changed :/
Very similar to what I put

Going back to a previous point, I agree that they test stupidly. Why not just ask us for loads of memorable information, instead of trying to screw us over with odd question wording! :P
20. (Original post by FiGuev)
pulse a was the crack and pulse b was the back of the screw
That's what I got...I'm surprised...everyone thought it was a hard exam but I didn't! The last question I found really easy aswell it's just total anticlockwise moment = total clockwise moment and you could work it out from there...! For the last one I got 375 N...

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