STEP II 2011 Discussion Thread

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Would you be expected to know the series expansions for STEP II though?Probably not. I'm pretty sure it's not the method they expected.

question 10 anyone?

Original post by Bork

Yep, STEP 1 in S111 on Friday.
I will definitely look at the mechanics sooner..

Haha who is this?

Reply 63

Piecewise

Original post by Webbykun

Well on the positive side, we've learnt from our mistakes and it should help us with STEP III/I

Except doing well on III/I will be of no use for those of us who were required required to get 1 on II. :tongue:

Reply 64

AnonyMatt

Original post by tobyc

I think if you let tan(x) be f(x), then the second derivative is equal to 2f'(x)f(x) so k has to be 2 when you're working with tan(x).

I feel a bit silly now, I had a similar problem with not being able to see what to do with that. Do you remember what your answer looked like? Because I did it a different (and much worse way). I wrote (tan(x)+sex(x))^6 as exp(6ln(tanx+secx)), because I was so pleased with myself when i remembered that sex(x) was the derivative of ln(secx+tanx) and then managed to integrate it in a similar way to how you derive that result in the first part of the question, using parts, although I had to use parts twice, and even then the integral I was left with was a multiple of the integral I started with, so I had to equate them and solve the equation.

It was all a bit messy and I could well have ended up with the wrong answer, did your answer have a factor of 35 in it somewhere by any chance? :s-smilie:

Sorry pressed reply too quickly - yes it had a factor of 35. Farhan has a full solution that is correct (as far as I've checked) on here!

It's annoying when you 'spot' a red herring. :p:

If I had known the derivative of ln|secx + tanx|, I'd have probably done exactly what you did! :colonhash:

Reply 65

jaheen22

I am kicking myself for lack of progress on the questions :frown:

Reply 66

Tsatska

Wow, I thought that was the hardest STEP 2 paper I've done! :O I did 1 (except solving the equation), 2 (the second part with trial and error but just read that candidates with the correct answer will get full marks despite method used :biggrin:

) and the last question about skewness. Although couldn't get out the inequality there... Anyone know what the average grade boundaries are for STEP 2? I need a two grade desperately!

Reply 67

thecakeisalie1

i thought question 2 was accesible enough but the rest of the pure was pretty hard q 8 was ridiculous

Reply 68

Zuzuzu

I've come to terms with the fact I'm not going to Cambridge now. Just hoping I can get a respectable mark in I and III so that the Sidney maths people don't have too much of a laugh looking at my scripts. :redface:

It's probably for the best anyway, if I could only scrape a 3 (at best) in step II, my head've exploded doing tripos exams.

Reply 69

kerribbz_x

Original post by soczek322

So who did questions 1,2,9 and 10??? Especially 9 and 10 the collisions and projectile questions?

I did 9 and 10 too!! What did you get for 10 mainly?! for the tanx?!

Reply 70

tobyc

Original post by AnonyMatt

Sorry pressed reply too quickly - yes it had a factor of 35. Farhan has a full solution that is correct (as far as I've checked) on here!

That's made me so happy :smile:

I've just looked at that solution, I can't remember if that's exactly what I got, but it looks similar, so hopefully that means I was close even if I made a slip somewhere.

I made a point to remember the 35 part so I could check later, because I thought it was unusual.

Reply 71

AnonyMatt

Original post by Piecewise

Except doing well on III/I will be of no use for those of us who were required required to get 1 on II. :tongue:

True.

Then again, since they look at your papers, maybe there's still a chance...

My paper is genuinely awful. The set out I mean!

The pages go like:

1,1,1,1,12,3,3,3,12,6,6,6,9,2,2,2,2,6,2,2 ADDITIONAL BOOKLET 6,6,2,6

So bloody awful - I'm so sorry Mr. Cambridge Person! :redface:

Reply 72

anttooking

Allthough Its hard to be subjective, Is it likey that the pass mark is likely to go to pre 2007 levels. i.e. 65 for a 1, 55 for 2... Or is it going to stay high?

Reply 73

soczek322

Original post by kerribbz_x

I did 9 and 10 too!! What did you get for 10 mainly?! for the tanx?!

root(2)/2?? and how did you prove that B is always moving towards the wall?

Reply 74

Schnecke

Original post by Zuzuzu

It's probably for the best anyway, if I could only scrape a 3 (at best) in step II, my head've exploded doing tripos exams.

This exactly.

Reply 75

.,james<>

Original post by soczek322

question 10 anyone?

For 10 I did the first part normally, to get the 'show that', did normal stuff then got stuck and came back to it later and then got when I realised you could sub. in the result from the first part. Last part I messed up I think. Can't remember how, but I think I decided that the downwards accelleration of P is 2g once the string is taught, using that i worked out the time taken for P to fall down to a height of 1/2H again. Reasoned that for R to be vertically bellow P at all times, the projection velocity of R must be uCos(theta), then multiplied this by the time to get D (which came out as a single fraction) then tan(theta)=2. I think this was good up to the 'show that' part, can't remember how I justified new acc. as 2g. Probably isn't.

Reply 76

Webbykun

Original post by anttooking

Allthough Its hard to be subjective, Is it likey that the pass mark is likely to go to pre 2007 levels. i.e. 65 for a 1, 55 for 2... Or is it going to stay high?

Frankly I found pre-2007 papers easier than this, this is the hardest I've ever tried. Perhaps it's just the pressure though.

Reply 77

Bork

Original post by Webbykun

Frankly I found pre-2007 papers easier than this, this is the hardest I've ever tried. Perhaps it's just the pressure though.

Same here, got 3 questions out on the 2002 paper and you only needed around 40 for a grade 2.
Hopefully the boundaries will be lower on this one too, but recently they seem to have been quite high.

Reply 78

kerribbz_x

Original post by soczek322

question 9 had to be done by everyone.... it was just m2? Except the last bit which I couldn't explain?

the last bit was using the fact that 0<e<1, and 0<f<1, and showing that the maximum and minimum velocity was positive so would be in the direction of the wall

Reply 79

tobyc

For all those who had trouble with the xcosecx thing, how many marks do you think we're likely to get for that question if we've done it right up to that point?

I think that difficult part cropped up halfway through, but seeing as the bits before seemed to be relatively straightforward, I'd imagine they'd be worth less than half marks, but I don't really know how the STEP marking works... :confused: