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OCR A forces fields and energy and synoptic paper thursday morning sign in here <---- watch

1. yea with that question you get one value for g by putting into the g=GM/r^2 the second value for g was a solution to the straight part of the graph where g and r were directly proportional, I did it by using basic laws of proportionality
2. farads and webers are si units, but not si base units from what i can work out
have a look at http://www.gordonengland.co.uk/conve...siderived1.htm and see what you think. i'm hoping that farad/weber etc were ok answers - but then i can't recall what the quesion asked (si unit or si base unit - does nayone have a copy in front of them?)
3. In my opinion, I think both should be allowed. The question was not clear in what it wanted and could be interpreted in two different ways. Another clear example of the absoulte joke that this synoptic paper is.
4. (Original post by rugbygraham)
Am I right in thinking that Farads, webers etc are not SI units? The only SI units are amp, joule, metre, second and kg, so you had to put the unit in terms of those for question 2 right?
i dont think so, i thought pascal is an Si unit for pressure, if thats ture then weber, tesla and bequrel must be right,
5. UC was hard, but comapared to other past papers it was one of the easiest, but in FFE who worked out teh mass of teh moon uestion??? what was that about.. that was the toughest bit rest was ok..
6. http://physics.nist.gov/cuu/Units/units.html

This shows that everything (including Pascal) can be derived from SI base units. The only mention I can find is in the Physics 1 Textbook, page 88 states ampere volt and ohm are 'SI units' (clearly they interpret SI unit there as derived SI units) whereas page 129 shows the relationship between units in the 'SI system' using only base units. I'm not making this point to try and prove I was right, as I think both points are equally valid BUT why write a question in that manner which was worded so poorly when even the textbook is inconsistent?

Would a letter to OCR make any difference? Or should I wait til I get my results (i.e. if I get a low mark write then, if not, not bother). I know its only 8 odd marks but in my opinion it sums up the entire paper.

Also, any chance of anyone getting the paper online?
7. I have the paper here-soz haven't got a scanner! but i completely undertsand both arguments because really speaking they are dervide SI units but the question specifically says....' for each of the following, give the full name of the SI units used' then there is only a small space along side-enough for one word really-so surely like gravitational field strength surely you couldn't write about four words for the newton derived unit and then like kg etc etc-the question is a bit vague!

the fact that it says give the full NAME is why i put farads etc, but i think they should allow both versions tbh!
8. (Original post by rugbygraham)
http://physics.nist.gov/cuu/Units/units.html

This shows that everything (including Pascal) can be derived from SI base units. The only mention I can find is in the Physics 1 Textbook, page 88 states ampere volt and ohm are 'SI units' (clearly they interpret SI unit there as derived SI units) whereas page 129 shows the relationship between units in the 'SI system' using only base units. I'm not making this point to try and prove I was right, as I think both points are equally valid BUT why write a question in that manner which was worded so poorly when even the textbook is inconsistent?

Would a letter to OCR make any difference? Or should I wait til I get my results (i.e. if I get a low mark write then, if not, not bother). I know its only 8 odd marks but in my opinion it sums up the entire paper.

Also, any chance of anyone getting the paper online?
I'm sure alternative answers will be allowed.
eg Becquerel or s-1
9. (Original post by Dabster)
yea with that question you get one value for g by putting into the g=GM/r^2 the second value for g was a solution to the straight part of the graph where g and r were directly proportional, I did it by using basic laws of proportionality
What was wrong with reading both off the graph as the values were given on the graph!! I thought that question was really strange.
10. nah the one closest to earth wasn't on the graph, 9.8 was, but not 0.098 because this was too small to read off the graph, it was a funny question though

what does everyone think about FFE you reckon it was harder/easier than january? any ideas if the grade boundaries will be as low?
11. (Original post by smurfride)
nah the one closest to earth wasn't on the graph, 9.8 was, but not 0.098 because this was too small to read off the graph, it was a funny question though

what does everyone think about FFE you reckon it was harder/easier than january? any ideas if the grade boundaries will be as low?
What were the grade boundaries in Jan?
I have no idea what they are generally.

Could anyone tell me roughly what an A is out of 90 raw marks for FFE and out of 60 marks for UC? Rep on offer.
12. I dunno tbh it's annoying because it seems as though other exam boards let their grade boundaries be known for papers over the years apart from OCR, i read earlier someone saying that january 06 an A boundary was 61/90 but it all depends whether this june one was considered easier than that or not i guess. Haven't got a clue about what the unifying concepts usually are
13. (Original post by Intelligentsia)
What was wrong with reading both off the graph as the values were given on the graph!! I thought that question was really strange.
the value for g that it had given was very small (0.098) i think that they purposly gave a small value and not a very accurate graph to see how you would work it out using mathematical skills, it was worthy of a unifying concepts paper.
14. I used g = GM/r^2, there were two values because of the + or - root of r, which you took away from the radius of the Earth. My answers seemed right because one was very small and the other was off the right of the graph. For those people who don't do maths i have no idea how they would have worked that one out.
15. I'm amazed anyone can remember what they actually wrote - but what Had wrote about the square root thingy giving a positive and negative value rings a bell somewhere in my head.
Now the pertinent (?sp) question here is how am I supposed to revise for HP with two chicken-pox riddled toddlers around my feet - and even worse, where am I supposed to put them while I do the exam cos the nursery won't have them!
I used g = GM/r^2, there were two values because of the + or - root of r, which you took away from the radius of the Earth. My answers seemed right because one was very small and the other was off the right of the graph. For those people who don't do maths i have no idea how they would have worked that one out.

yea i know what you mean but from the question i get the impression that they've given some clues and considering its only worth 2 marks-i thought a very straightforward way was to take the point at which g = 9.8 divide both values by 100, I'm pretty sure that's acceptable because the line is straight.I think they've given clues as to this because it's just the first most straighforward thing i could think of, I thik they did this knowing that alot of people wouldn't think of the +/- thing!
17. for that one i think your were supposed to use the graph and from the graph you could tell that there were two parts eg the straight line part had a value for 0.098 and the other part was the curve which u used the forumula
18. (Original post by investor)
for that one i think your were supposed to use the graph and from the graph you could tell that there were two parts eg the straight line part had a value for 0.098 and the other part was the curve which u used the forumula
yea thats exactly how i did it
19. has anyone read the examiners report for the ocr physics a-level 2005? cos we were looking through it in class a while ago and I'm sure we worked out that only two people got an A at a-level physics that year... but thinking about that now, it just seems ridiculous so im guessing/hoping we made a stupid mistake
20. (Original post by Dabster)
yea thats exactly how i did it
what did you get for the straight line bit ?? i think i got the gradient as 1.6 or something and equated it wth y=mx+c and as it passed through origin there was no C and then i just

1.6x0.098 or something

when do we find out our marks for them ??

are you sure that only 2 people got A ?? its usually the top 30% will get an A then next 30% B and so on roughly along those lines

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