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# Edexcel M4 - How was it? watch

1. Me and my friends just came out the M4 exam - and we didn't like it at all. Talk about saving the worst till last. It was the hardest M4 paper I have ever seen. No, actually it was the hardest maths paper that I have ever seen. So, how did everyone else find it?
2. (Original post by Hingy)
Me and my friends just came out the M4 exam - and we didn't like it at all. Talk about saving the worst till last. It was the hardest M4 paper I have ever seen. No, actually it was the hardest maths paper that I have ever seen. So, how did everyone else find it?

Fresh from Satan's backside to your desk!

- Q1 took too long to interpret, even though the maths was easy.
- Q2 was OK (I and my friends all got 1/3, so we're pleased we at least scored something!).
- Q3 seemed pretty standard, though I'd have liked to have practiced ones like it more. I got around 13:06 and 2.07km. May be wrong, though.
- Q4 was pretty standard, and came out OK.
- Q5, proving the equation was fine. They took all the fun and marks out of it by giving you the general solution. I ended up with some nonsense like D = kC, and from then on screwed up...
- Q6, proving was fine. I couldn't do the integral, as I never tried substitution (no M4 questions I've seen in the past have integrals like that). If I had, it could have worked. Finding the time, I took the original formula, changed to v(dv/dt) and integrated, getting a mess that I re-arranged in terms like (v-k)ln(v-k), as I ended up using parts. I do believe that this is wrong!

Thus, I thought it was foul - perhaps worse than Tuesday's P6. Expecting the worst, I'm guessing about 40/75, or around only 60 UMS for it (though there may be quite a boost).

Is a viable combination of options:
Maths: P1, P2, P3, M1, M4, S1
F Maths: P4, P5, P6, M2, M3, S2
?
3. I had M4 and thought it was impossible.

I did the first question, eventually and for the other vectors question I ended up with really round numbers, 14.4 km I think was one of them, but thats different from yours. The rest I screwed up. I didn't get 1/3 for the restitution coeffecient I got something with tan in it, so hopefully the UMS will be marked up considerable I need like 40% for an A overall I think.
4. I can't believe how few questions I could actually answer! It was atrocious! + you needed bout 1hr more! AWFUL! I was hoping that it would be plane sailing!
5. ne1 done M6 today? and how was it?
i found it absolutely impossible, except Q6 which was very easy.
6. Awful. Worse than last summer's P3 paper. Some parts were OK but every question seemed to have a twist to it. With those type of questions, they don't let you use your knowledge of the topics in the way that more straightforward questions would. Too much time is spent deciphering the question!
7. (Original post by Werther)
Fresh from Satan's backside to your desk!

- Q1 took too long to interpret, even though the maths was easy.
- Q2 was OK (I and my friends all got 1/3, so we're pleased we at least scored something!).
- Q3 seemed pretty standard, though I'd have liked to have practiced ones like it more. I got around 13:06 and 2.07km. May be wrong, though.
- Q4 was pretty standard, and came out OK.
- Q5, proving the equation was fine. They took all the fun and marks out of it by giving you the general solution. I ended up with some nonsense like D = kC, and from then on screwed up...
- Q6, proving was fine. I couldn't do the integral, as I never tried substitution (no M4 questions I've seen in the past have integrals like that). If I had, it could have worked. Finding the time, I took the original formula, changed to v(dv/dt) and integrated, getting a mess that I re-arranged in terms like (v-k)ln(v-k), as I ended up using parts. I do believe that this is wrong!

Thus, I thought it was foul - perhaps worse than Tuesday's P6. Expecting the worst, I'm guessing about 40/75, or around only 60 UMS for it (though there may be quite a boost).

Is a viable combination of options:
Maths: P1, P2, P3, M1, M4, S1
F Maths: P4, P5, P6, M2, M3, S2
?
It was ok I thought - not too bad in the end but I couldn't do quite a few parts the first time through. I got e=1/5 and was really pleased as it seemed a nice answer, but everyone else got 1/3!!

Q3 - I got 1 hour 6 mins (didn't notice it started at noon!)

Q5 - D=kC was right, then you had to do v = 0, get t = (pi)/k For the show that at the end, you put x>0 at t=(pi)/k and work through to get the right inequality

Q6 - For the integral you needed to do long division v^2 = -v(k-v) + kv = -v(k-v) - k(k-v) + k^2 so v^2/(k-v) = -v - k + k^2/(k-v) then integrate from there. For the time I said a = dv/dt then rearranged and integrated wrt t

That combination looks fine
8. [/QUOTE]
Q5 - D=kC was right, then you had to do v = 0, get t = (pi)/k For the show that at the end, you put x>0 at t=(pi)/k and work through to get the right inequality
[/QUOTE]

I assume then I'll get the marks for the constants, so it's not that bad. The fact that the result looked such a mess caused me to panic, so I muddled the end of the question... t = pi/k isn't that hard to get, really... I ignored the inequality part as I was running out of time, and thought I'd be able to make it up by doing a nice easy integral...

[/QUOTE]
Q6 - For the integral you needed to do long division v^2 = -v(k-v) + kv = -v(k-v) - k(k-v) + k^2 so v^2/(k-v) = -v - k + k^2/(k-v) then integrate from there. For the time I said a = dv/dt then rearranged and integrated wrt t
[/QUOTE]

I knew I could have done the integral, but in the stress of the exam, I found I wasn't able to think straight, and get a division to work. Other people managed it with a substitution. What did you get for time? My answer was a very hurried integration, so I'm guessing I've slipped - I ended up using parts, then having to use the standard parts result to integrate ln(k-v). I'm assuming most it's incorrect.

[/QUOTE]
That combination looks fine[/QUOTE]

Phew... No matter how badly I've done in M4, I should still be able to get two As by sticking it on single maths. I only need an A in Further Maths, but I'd hope to avoid having to fiddle to obtain this, and thus not have a viable single maths grade (hence six wasted modules).
9. (Original post by Werther)
What did you get for time?
I can't really remember. It was similar to the other one, something like 1/g*(ln[k/(k-v)] + a couple of other bits)
10. What I didnt get about the last question was that after you got x = f(v) how to use 'hence' to get t = g(v). Instead i just went back to the initial equations and did the question from scratch using m.dv/dt = F
11. That was infinitely worse than last year's P3. At least I finished the P3 last year. I felt like meeting my nemisis. Terifying... absolutely terifying.
12. Yep, that was an evil paper. The best in the class, even with his (unfair) extra time didn't finish the paper.

I got a root 3 in my e, so I'm different again. I didn't notice the stability question had an isoceles triangle so I didn't manage the equation, which I'm annoyed about.

There seemed many more marks than usual for the actual mechanics and less for the pure, e.g. giving us the general solution for the 2nd order diff. eqn..

Oh well, no more now anyway, and I did always find M4 hardest. It's nice to know everyone else found it tough too, in a way :-). Though I prefer to be able to do the questions... I only completed the spheres one, the rest all had big problems :-(

Worst maths paper I've seen.
13. (Original post by chaoscomplex)
Worst maths paper I've seen.
You obviously didn't do STEP III then...
14. (Original post by It'sPhil...)
You obviously didn't do STEP III then...
I liked STEP III better......

You doing STEP II tomorrow?
15. (Original post by Camford)
I liked STEP III better......

You doing STEP II tomorrow?
Seriously!? Yeah i have II tomorrow. Not too worried as i usually find II a lot nicer than III
16. oh dear oh dear mine went absolute turd.

I am so cross.; The whole thing was so incredibly evil. Instead of testing you on what M4 was about they decided it would be fun to put in lots of crappy wired things!!!!!!!!!!! ARGH. And then they made is so flippin complicated to read and understand what the hell it was all really about!!!!! And putting it in July as well, School in Northern ireland finishes in june so my head was just roasted. Its not the fact that they put stuff on i could do annoyed me - like thats the purpose of exams... But to put stuff on that requires you to go through stupid integrals and solutions that take ages annoy me. I only got the energy question right the rest of the paper went to pot. I HATE EDEXCEL. I HATE EXAMS...I HATE ALEVELS and most of all IM FINISHED...rant over...

Oh and where the the 1/2v^2 or whatever come from in the last question...

Rant Now Definately over...I think its cost me my A in A level
17. (Original post by It'sPhil...)
What I didnt get about the last question was that after you got x = f(v) how to use 'hence' to get t = g(v). Instead i just went back to the initial equations and did the question from scratch using m.dv/dt = F
I couldn't see any way of getting from x = f(v) to t = g(v) either - at least it said hence or otherwise! I did the same as you using a = dv/dt and integrating again. I seem to recall the integral wrt t was part of the integral wrt v so they may have meant use that part of the integral that you'd already done? Seemed weird though
18. (Original post by Bezza)
I couldn't see any way of getting from x = f(v) to t = g(v) either - at least it said hence or otherwise! I did the same as you using a = dv/dt and integrating again. I seem to recall the integral wrt t was part of the integral wrt v so they may have meant use that part of the integral that you'd already done? Seemed weird though
Yeah because the result turned out very similar (minus the -1/2v^2 and divided by a factor of k) so there was maybe some easy link. I spent about 10 mins writing out on scrap every weird combination of derivatives of v t and x to try and get somewhere. In the end I gave up , wrote "otherwise..." on my script and did it the 'long' way, which turned out to be only 2/3 of a side.
19. Yeah i just did the otherwise as well... can anyone enlighten us on the (proberbly stupidly easy) hence method.
20. (Original post by Valen)
Yeah i just did the otherwise as well... can anyone enlighten us on the (proberbly stupidly easy) hence method.
I can only see another method which only really works when you have the answer

You know that gx = k²ln(k/(k-v)) - kv - v²/2

Therefore gx/k + v²/2k = kln(k/(k-v)) - v

Consider d/dt(gx/k + v²/2k ) = 1/k(g.dx/dt + v.dv/dt)

= 1/k(gv + v.dv/dt) But you know that v.dv/dt = (k-v)g so v.dv/dt + gv = gk

Therefore d/dt(gx/k + v²/2k ) = g, in other words gx/k + v²/2k = gt

So... gt = kln(k/(k-v)) - v

Probably slightly shorter than the otherwise method, but pretty random and I would never think of doing that if I didn't already know the answer would be very similar

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