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# P6 ... say what ? ... watch

1. (Original post by ybx)
i just need get ready for M6 on thursday, althougth i didn't really need it
How does M6 compare to M5 and M4? My FM class wanted to do M6, but the school made us do S1 (yuck!) instead.

P6 wasn't so bad, I didn't like the induction proof either, I did differentiate correctly but I couldn't get the trig out, though I got the 2^½n bit. So I wrote what should have happened. The last question was bad too, I couldn't get (a) out. The rest might be OK.

And I've lost the marks for describing the matrix transformation, we never covered how they transform in class, only the calculations, so I guessed rotations and magnifications in some order.

Just M4 now
2. (Original post by It'sPhil...)

= det
(-1 0 )
( 0 -1)

= (-1)X(-1) = 1
i was talking about a 3x3 matrix
3. (Original post by chaoscomplex)
How does M6 compare to M5 and M4? My FM class wanted to do M6, but the school made us do S1 (yuck!) instead.

P6 wasn't so bad, I didn't like the induction proof either, I did differentiate correctly but I couldn't get the trig out, though I got the 2^½n bit. So I wrote what should have happened. The last question was bad too, I couldn't get (a) out. The rest might be OK.

And I've lost the marks for describing the matrix transformation, we never covered how they transform in class, only the calculations, so I guessed rotations and magnifications in some order.

Just M4 now
I would say M6 is easier than M5 and M4. There are only 3 topics on it for a start, but you need a good knowlage of polar coordinates and intrinsic coordinates for the first 2, and the rotational motion stuff from M5 to do the last topic.

And you get given a lot of the results in the formula booklet. See Mechanics 2D General Motion.

The first 2 topics are on the motion of particles which can be described by curves, be it polar or intrinsic, and the forces that act on them. For example radial acceleration (like in a circle) is V^2 over the radius of curvature as opposed to V^2 over R (which is in fact the same thing!).

The last topic is basicly about combining all the rotational stuff from M5 with all the linear stuff studied before it, and its kinda satisfying the way it joins it all together so you can have objects moving and rotating.
4. (Original post by Valen)
The last topic is basicly about combining all the rotational stuff from M5 with all the linear stuff studied before it, and its kinda satisfying the way it joins it all together so you can have objects moving and rotating.
That's good, I didn't realise it joined it all together. Pity we don't do it, S1 was amazingly dull.

On the plus side I only have 1 exam tomorrow
5. That p6 paper was generally hard. After skipping a few parts i finished the paper in 1hr. I then came back and done most (as it didn't get the exact answer) of the proof question, which looked impossible at first and corrected many stupid mistakes due to panicing.
I had no idea what to write about that 4 mark matrix transformation question, as i had never come across this before, so i just made any rubbish up.

P4 was harder then January but i could do all the questions eventually. This is porbably due to a lack of revision as its a resit.

Overall it went okay. The way i see it is, it could have gone alot worse.
6. as far as Q5 goes, i got a, b and c to be 2, 1 and -2, K was 18
...
good thing about working out the dets is that my calculator can do matrix stuff, so it's easy to check (assuming you get a, b, c correct, of course - but it avoids errors in working), so i got the det as -54

i thought that question was quite nice, except i'm fairly certain that i wrote down "k = 1/18" for some bizarre reason :|
the induction question.. i managed (like most it seems) to do it for n=1 as a test, and i got part way through proving it i think, maybe, but it wasn't a style of induction that i'd ever seen before. i'd certainly never done that from any examples in the edexcel text book.
nasty paper imho, STEP 1 was easier \o/
7. Can anyone tell me what answers he/she got for the question 6? What combination of transformations was R and what was the matrix P?
8. (Original post by A2 student)
Can anyone tell me what answers he/she got for the question 6? What combination of transformations was R and what was the matrix P?
not absolutely sure but i think clockwise rotation, stretch, anticlockwise rotation
9. what was the angle of the rotation?
10. (Original post by A2 student)
what was the angle of the rotation?
45 ( you should have got some root2 s in your normalised eigenvectors)
11. I Got The Same
12. So they asked for normalised eigenvectors in the question? I have good luck.I normalised my eigenvectors without reading the question thoroughly because I was short of time and after the exam I started to wondewr whether the question stated that I should normalise my eigenvectors or not and I was really afraid that it did not ask for normalised eigenvectors.
13. (Original post by A2 student)
So they asked for normalised eigenvectors in the question? I have good luck.I normalised my eigenvectors without reading the question thoroughly because I was short of time and after the exam I started to wondewr whether the question stated that I should normalise my eigenvectors or not and I was really afraid that it did not ask for normalised eigenvectors.
If it didn't ask for them, you wouldn't be marked down for normalising anyway. I forgot to mention it was rotated back after it was stretched, doh!
14. (Original post by It'sPhil...)
not absolutely sure but i think clockwise rotation, stretch, anticlockwise rotation
i put anticlockwise rotation by 45 deg first, then stretch and clockwise rotation by 45 deg

EDIT: maybe it depends on the diagonal matrix used
15. I thought you were supposed to normalise them if you wanted to make the diagonal matrix.

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