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Edexcel Mathematics: Mechanics M3 6679 01 - 17 May 2017 [Exam Discussion]

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i don't think grade boundaries would be as high as last years.... a lot of people seem to make the mistake that 6. was horizontal. As well as realising the string broke in the last question so it was constant speed.
Original post by itrytohard
i don't think grade boundaries would be as high as last years.... a lot of people seem to make the mistake that 6. was horizontal. As well as realising the string broke in the last question so it was constant speed.

I assume you mean people think that its vertical for q6 which is wrong ( i was wrong aswell for putting mgh in ). And yeah i think boundaries wouldnt be high since there was a lot tricky questions but overall it was a good paper for me, expecting 5, 6 marks off
Original post by itrytohard
i don't think grade boundaries would be as high as last years.... a lot of people seem to make the mistake that 6. was horizontal. As well as realising the string broke in the last question so it was constant speed.


yh I'm guessing 70-A* and 67-A hopefully, think i dropped about 6 marks. so will have just missed the A* , guess ill have to make up for it in M2/FP2 now hopefully.
how many marks was q 3???
Original post by JJSinha
Yeah. You find the smallest value of v^2. Then if R>0 for this value, the particle stays in contact.
It was 7+ 2sin (theta) though, not 3.


Many thanks for checking this one for me. I must have made a slip up with the algebra to get 3 instead of 2 but good to know that I've at least answered the question with the correct idea in mind. Hopefully will bag most of the marks for this.
Original post by dididid
yh I'm guessing 70-A* and 67-A hopefully, think i dropped about 6 marks. so will have just missed the A* , guess ill have to make up for it in M2/FP2 now hopefully.


Dont panic, I dont think the grade boundaries will be that high for an A grade. It should be around 64/75 - A and 70/75 - A*

You have to consider that many people that use this site are of the best, if you break down the exam you can see where the average candidate could lose marks:

Q1 - Volume of revolution by accident
Q2 - This was stupidly easy for 8 marks
Q3 - Easy to make a mistake here, I used the M4 method of creating an equation of motion and then using vdv/dx
Q4 - The amount of people that will get this question wrong, mainly due to misreading the question (thinking it was solid) or not including the base of the cylinder when calculating centre of mass of hollow cylinder (many people would have assumed this was 4a/2)
Q5 - Again, people thinking this was vertical, not considering the EPE when the string was at AB, using the wrong length etc.
Q6 - Fairly easy overall, however I lost a mark here for considering the reaction to be R>/=0, which is not true, it should be R>0
Q7 - This question would be unavailable to a weak candidate, proving the length isn't too bad, proving the SHM is easy if you know what to do but you have to be careful, finding the time overall provides a lot of room for error.

Overall I think I have scored 72 or 73

Good luck for your other exams, I'm hoping to get an A* with that combo also, M2M3FP2
Original post by xyz9856
Dont panic, I dont think the grade boundaries will be that high for an A grade. It should be around 64/75 - A and 70/75 - A*

You have to consider that many people that use this site are of the best, if you break down the exam you can see where the average candidate could lose marks:

Q1 - Volume of revolution by accident
Q2 - This was stupidly easy for 8 marks
Q3 - Easy to make a mistake here, I used the M4 method of creating an equation of motion and then using vdv/dx
Q4 - The amount of people that will get this question wrong, mainly due to misreading the question (thinking it was solid) or not including the base of the cylinder when calculating centre of mass of hollow cylinder (many people would have assumed this was 4a/2)
Q5 - Again, people thinking this was vertical, not considering the EPE when the string was at AB, using the wrong length etc.
Q6 - Fairly easy overall, however I lost a mark here for considering the reaction to be R>/=0, which is not true, it should be R>0
Q7 - This question would be unavailable to a weak candidate, proving the length isn't too bad, proving the SHM is easy if you know what to do but you have to be careful, finding the time overall provides a lot of room for error.

Overall I think I have scored 72 or 73

Good luck for your other exams, I'm hoping to get an A* with that combo also, M2M3FP2


Is that GCE or IAL?!
Original post by WhiteScythe
MS

1. 3/4
2. theta = 33.6 (degrees) l = 0.2m
3. (a) 4.52ms^-1 (b) 5.42m
4. (a) 25/11a (b) theta =23.7 (degrees)
5. (b) 5mg>mg (c) v(max) = 3sqrt(ga)
6. (b) F=38.4N (c) v=6.5ms^-1
7. (a) AO =2.2m (b) a = -625/9x (c) T=1.02 seconds


Which paper are these answers for GCE or IAL?
Original post by hasi.99
Is that GCE or IAL?!


GCE (Uk)
Does anyone remember how many marks the 'prove that the particle moves in circles' bit was? I messed up and showed that v>0 at the top and forgot about tension...
Original post by xyz9856
Dont panic, I dont think the grade boundaries will be that high for an A grade. It should be around 64/75 - A and 70/75 - A*

You have to consider that many people that use this site are of the best, if you break down the exam you can see where the average candidate could lose marks:

Q1 - Volume of revolution by accident
Q2 - This was stupidly easy for 8 marks
Q3 - Easy to make a mistake here, I used the M4 method of creating an equation of motion and then using vdv/dx
Q4 - The amount of people that will get this question wrong, mainly due to misreading the question (thinking it was solid) or not including the base of the cylinder when calculating centre of mass of hollow cylinder (many people would have assumed this was 4a/2)
Q5 - Again, people thinking this was vertical, not considering the EPE when the string was at AB, using the wrong length etc.
Q6 - Fairly easy overall, however I lost a mark here for considering the reaction to be R>/=0, which is not true, it should be R>0
Q7 - This question would be unavailable to a weak candidate, proving the length isn't too bad, proving the SHM is easy if you know what to do but you have to be careful, finding the time overall provides a lot of room for error.

Overall I think I have scored 72 or 73

Good luck for your other exams, I'm hoping to get an A* with that combo also, M2M3FP2

Hi, how many marks do you think I lose for 5c if i assume it was vertical ? I wrote down everything but include mgh aswell :/
I'm hoping for 71. I got part of the finding centre of mass with the cylinder and hemisphere wrong.

Knowing my luck though I probably messed something else up :frown:
Original post by anhkiet1903
Hi, how many marks do you think I lose for 5c if i assume it was vertical ? I wrote down everything but include mgh aswell :/


I would expect at least two, maybe three.
A1- incorrect final value of V
M1-incorrect equation of motion
B1 -incorrect equation of motion

If I remember correctly the question was out of 5, you may have scored 2/5 sorry :frown:
The paper was pretty standard, although I can see how some students could make mistakes so I don't think it will be the same grade boundaries as last year. I think 70 for 90UMS is a fair prediction.
It's interesting how the word "horizontal" was printed in bold I think twice yet still people thought it was extended vertically...

Q2 was a joke.
Original post by xyz9856
I would expect at least two, maybe three.
A1- incorrect final value of V
M1-incorrect equation of motion
B1 -incorrect equation of motion

If I remember correctly the question was out of 5, you may have scored 2/5 sorry :frown:


It was out of 6 haha, so i might get 3 or 4 out of 6 then. Man i think i might miss the A* since i lose around 5-6 marks for this paper :/. Oh well gotta try harder, but thanks anw :biggrin:
Original post by Strom
I'm hoping for 71. I got part of the finding centre of mass with the cylinder and hemisphere wrong.

Knowing my luck though I probably messed something else up :frown:

I made the same mistake as you. You think we'd only lose 4 marks? There was a part b, calculating the angle, surely we would lose marks on there as well.
Original post by anhkiet1903
It was out of 6 haha, so i might get 3 or 4 out of 6 then. Man i think i might miss the A* since i lose around 5-6 marks for this paper :/. Oh well gotta try harder, but thanks anw :biggrin:


Personally, I believe it was an ok paper, the grade boundaries will be high but not as high as last years 69/70 for an A*.

Last years exam was stupidly easy imo. Was it just me, or question two on this exam took about 1 minute to answer? I was genuinely shocked when I saw it was 8 marks
Original post by xyz9856
Personally, I believe it was an ok paper, the grade boundaries will be high but not as high as last years 69/70 for an A*.

Last years exam was stupidly easy imo. Was it just me, or question two on this exam took about 1 minute to answer? I was genuinely shocked when I saw it was 8 marks


Yeah that question was a joke. When i saw they give you omega, i was expecting its gnna be tricky since you dnt usually get that. But then they give you tension aswell so it was hella easy
Original post by Orlandothefraser
I made the same mistake as you. You think we'd only lose 4 marks? There was a part b, calculating the angle, surely we would lose marks on there as well.


If you made a mistake and got the wrong value for the distance of the C.O.M in part a) then in part b) you would only lose 1 A mark in calculating the angle provided your method was correct.
(edited 6 years ago)

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