Edexcel M2/M3 June 6th/10th 2013

They have appeared now. I've done the UK one (see below). I'm just starting the international one.

For the UK one, I think I agree with Idknow on everything except 7(c), where you needed to get the answers in terms of a, g and t only.

It got pretty tough towards the end, didn't it?

you done goofed on the integration, should be 1094/15, which ends up with the same answer to 3sf, so its really just pendantry on my part ^^

Edit: actually it affects 5b somewhat

(edited 10 years ago)

Reply 781

cant_think_of_name

15

Original post by MAD Phil

They have appeared now. I've done the UK one (see below). I'm just starting the international one.

For the UK one, I think I agree with Idknow on everything except 7(c), where you needed to get the answers in terms of a, g and t only.

It got pretty tough towards the end, didn't it?

Cheers man, I'm out of rep but that looks good :smile:

I think I got everything except 5 b, can't work out exactly what I did wrong (possible rounding errors on my part) but my answer was like 0.65 or something. Hopefully a couple of marks only lost there. Thanks again! :cool:

Reply 782

noob27

Original post by MAD Phil

They have appeared now. I've done the UK one (see below). I'm just starting the international one.

For the UK one, I think I agree with Idknow on everything except 7(c), where you needed to get the answers in terms of a, g and t only.

It got pretty tough towards the end, didn't it?

Thanks for this - had a bit of a query with 7c though - isn't the initial x-coordinate asin(alpha) and the intial y-coordinate acos(alpha) from your diagram, not the other way round?

Reply 783

noob27

Original post by cant_think_of_name

Cheers man, I'm out of rep but that looks good :smile:

I think I got everything except 5 b, can't work out exactly what I did wrong (possible rounding errors on my part) but my answer was like 0.65 or something. Hopefully a couple of marks only lost there. Thanks again! :cool:

Yeah I got the same as you there, around 0.65ish, not sure what I did either

Reply 784

cant_think_of_name

15

Original post by noob27

Yeah I got the same as you there, around 0.65ish, not sure what I did either

Hmmm, strange. I might try the question later again if I have time

But then again maybe not, due to having S3 on Thursday :tongue:

Reply 785

Boy_wonder_95

15

Original post by JenniS

...

How was M3?

Reply 786

MAD Phil

Original post by MAD Phil

They have appeared now. I've done the UK one (see below). I'm just starting the international one.

For the UK one, I think I agree with Idknow on everything except 7(c), where you needed to get the answers in terms of a, g and t only.

It got pretty tough towards the end, didn't it?

These papers contain some quite awkward questions, and seem quite long. (But partly that's just me trying to get exact answers when any sane person in an exam would be using a calculator.)

I haven't checked the international one at all, so there will probably be even more mistakes in that. (See below.) I'll check out the errors found in the first one now, and answer other points after that.

EDIT: I've made corrections needed because of mistakes pointed out by about 1 pm today, Wednesday. The new version is now with the corrected version of the UK paper answers, at the post that this one is replying to.

(edited 10 years ago)

Reply 787

YDQ

6

Original post by MAD Phil

These papers contain some quite awkward questions, and seem quite long. (But partly that's just me trying to get exact answers when any sane person in an exam would be using a calculator.)

I haven't checked the international one at all, so there will probably be even more mistakes in that. (See below.) I'll check out the errors found in the first one now, and answer other points after that.

Hey,

Really confused about this- how comes there is a UK version of the paper and an Int'l. version? Thought we all did the same exam?

Reply 788

goodkwong

Original post by MAD Phil

These papers contain some quite awkward questions, and seem quite long. (But partly that's just me trying to get exact answers when any sane person in an exam would be using a calculator.)

I haven't checked the international one at all, so there will probably be even more mistakes in that. (See below.) I'll check out the errors found in the first one now, and answer other points after that.

For the international one:
Q2: should be 90J
when sub. t=4, v=7 rather than 5

Reply 789

MAD Phil

Original post by The Burgeoning

you done goofed on the integration, should be 1094/15, which ends up with the same answer to 3sf, so its really just pendantry on my part ^^

Edit: actually it affects 5b somewhat

You're right - the final answer should be 1191/1652 = 0.721, not 0.722. Until recently, our college insisted on students using quite old-fashioned calculators which wouldn't do definite integrations. I was one of the main people pushing to lift the restriction because it was disadvantaging our students, but clearly I haven't got used to the change myself. I'll edit my answers to do it the sensible way later.

Reply 790

goodkwong

Original post by MAD Phil

These papers contain some quite awkward questions, and seem quite long. (But partly that's just me trying to get exact answers when any sane person in an exam would be using a calculator.)

I haven't checked the international one at all, so there will probably be even more mistakes in that. (See below.) I'll check out the errors found in the first one now, and answer other points after that.

For Q5:
Answer should be 0.5497
(1/2)g(t^2)= (1/2)(49/5)(t^2) rather than just (49/5)(t^1/2)

I had got the same answers for all other questions(but making silly mistakes during the exam)

For Q6:
I would like to know how many marks would I lose if I use "a" rather than "a/2" in Q6 for CG of the rectangle when calculating the CG of lamina in part (b)...then in part(c)...

May I still get the method marks of part (b) and (c) = 2+1 = 3 marks (or more?) out of 8?

For Q5:
And I would also like to know if I get the time wrong in Q5 because when I use both [ v^2=u^2 - 2gh ] and [ v=u+at ] to find time t, I wrote "2gh" into "gh" forgetting to add the "2", leading to wrong time t and thus wrong ans of 0.515m.

Would I still get the method marks of about 4 out of 8?

(edited 10 years ago)

Reply 791

oli_G

12

Original post by MAD Phil

These papers contain some quite awkward questions, and seem quite long. (But partly that's just me trying to get exact answers when any sane person in an exam would be using a calculator.)

I haven't checked the international one at all, so there will probably be even more mistakes in that. (See below.) I'll check out the errors found in the first one now, and answer other points after that.

Isn't the radius of the sphere in the COM question 0.5cm not 1 cm -this changes the final answer substantially?

Reply 792

MAD Phil

Original post by noob27

Thanks for this - had a bit of a query with 7c though - isn't the initial x-coordinate asin(alpha) and the intial y-coordinate acos(alpha) from your diagram, not the other way round?

I might be wrong, but I don't think so. The little diagram on the last page is just a unit-circle diagram to establish which value of theta I was looking for. (You look for intersections with x = a to solve cos(theta) = a and with y = b to solve sin(theta) = b.) Because these unit circle diagrams conventionally measure theta anticlockwise from the rightwards horizontal, and the question measures theta clockwise from the downward vertical, the little diagram is rotated 90 degrees compared to the main diagram.

In fact, to avoid this confusion, (compounded by the fact that according to their diagram, the critical value of theta is negative), I almost decided to do the Newton and CofE again, instead of using the result proved in (a).

Reply 793

cant_think_of_name

15

Original post by oli_G

Isn't the radius of the sphere in the COM question 0.5cm not 1 cm -this changes the final answer substantially?

No, it is 1 I think, because the y co-ordinate of the shape thingy from part (a) is 1.

Reply 794

KD35

15

the radius is definately 1.

the equation was y=(x+1)^2

It crosses y axis as y=1 and as it is rotated around the x axis, the two end points are 1 and -1.

Reply 795

MAD Phil

Original post by YDQ

Hey,

Really confused about this- how comes there is a UK version of the paper and an Int'l. version? Thought we all did the same exam?

Different ones for different time-zones, so people don't have to go into purdah for ages while waiting for people on the other side of the world to finish the paper.

Reply 796

oli_G

12

Original post by KD35

the radius is definately 1.

the equation was y=(x+1)^2

It crosses y axis as y=1 and as it is rotated around the x axis, the two end points are 1 and -1.