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

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Original post by goatygoat
Shouldn't you be happy about that? :mmm:


Not to an M3 paper. :smile::smile:
Lets go optic
lets go optic
I saw someone post a website with more past papers on this forum and decided to check them out but the mark schemes seem to be wrong or is it me? http://crashmaths.com/a-level-practice-papers/ - paper a seems to have loads of mistakes in their solutions ;/
Can that vector notation in chapter 4 come up and deriving from first principles 2rsinA/3A ?
Original post by TrueDAN
Can that vector notation in chapter 4 come up and deriving from first principles 2rsinA/3A ?


I'm not sure about the vector stuff, I just thought it was used as an easy way for us to understand where the equations come from.

In the textbook for the 2rsinA/3A proof it just says "You should understand and learn how to derive it", so I assume it could :/
Original post by LukeB98
I'm not sure about the vector stuff, I just thought it was used as an easy way for us to understand where the equations come from.

In the textbook for the 2rsinA/3A proof it just says "You should understand and learn how to derive it", so I assume it could :/


Ah okay thank you mate - that proof one is pretty insane - ive just memorised how
madasmaths did it just in case it comes up, cheers
Any predictions?
hey, can someone help me with question 1 on jan 16 (IAL) I'm probably missing something obvious but I can't see how you would find the angle to the horizontal , the mark scheme shows it as being 60 degrees but dosent show how. Screen Shot 2017-05-16 at 15.24.20.png
what proofs do we need to learn?
Original post by dididid
hey, can someone help me with question 1 on jan 16 (IAL) I'm probably missing something obvious but I can't see how you would find the angle to the horizontal , the mark scheme shows it as being 60 degrees but dosent show how. Screen Shot 2017-05-16 at 15.24.20.png


draw a line of the particle to the centre of the hemisphere - that'll be radius 2r .
Original post by dididid
hey, can someone help me with question 1 on jan 16 (IAL) I'm probably missing something obvious but I can't see how you would find the angle to the horizontal , the mark scheme shows it as being 60 degrees but dosent show how. Screen Shot 2017-05-16 at 15.24.20.png


arccos(r/2r) = 60 degrees
Can someone help me on example 14 chapter 4
Original post by Major-fury
draw a line of the particle to the centre of the hemisphere - that'll be radius 2r .


Original post by saira.p
arccos(r/2r) = 60 degrees


ahhh, thanks . lol yh i was missing something very obvious
Original post by saira.p
what proofs do we need to learn?


For chapter five (statics/CoM) if you have the textbook to hand it's probably worth learning examples 4, 7, 10, 11 and maybe 13. Also worth looking at some questions involving triangular laminas, seen a few of those come up.

Don't think we need to know anything else. It's worth having memorised the way to prove simple harmonic motion.
Original post by dididid
ahhh, thanks . lol yh i was missing something very obvious


Could you help me on shm questions? how to find the direction of x increasing in some cases.
Original post by Ash8991
Any predictions?


- First principle COM derivation / intergation for COM and some grim c.o.m moments question - probably one weve never seen before.
- Hopefully just a standard calculus question and nothing out of the ordinary.
- Potentially a gravitational problem as it has not came up a lot recently.
- Im thinking a string/spring on a rough plane (maybe inclined) to test our knowledge of the work energy principle
- Obviously SHM - they like the ones were they are 2 strings with different natural lengths horizontal.
- Standard circular motion question with the need for SUVAT in some part or maybe looking at least and greatest tensions and showing something.
- Would love a banked track question/ nice banked circular motion too.
Just guessing though, no idea tbh - probably every scenario ive mentioned wont come up tomorrow haha
Original post by Major-fury
Could you help me on shm questions? how to find the direction of x increasing in some cases.


yh sure ,
Original post by dididid
yh sure ,


June 2013, June 2013 R, typically those types of questions i can't tell when it just states that it's released from rest...
When you have a w^2 value having proved s.h.m, do you have to leave it to 3 sf if you have used g? The mark scheme seems really anal about giving too much precision but with this it looks like you can leave it as a fraction ?
Original post by the___jackal
When you have a w^2 value having proved s.h.m, do you have to leave it to 3 sf if you have used g? The mark scheme seems really anal about giving too much precision but with this it looks like you can leave it as a fraction ?


unless stated to give to a degree of accuracy , I'm pretty sure you can leave as a fraction with g .


Original post by Major-fury
June 2013, June 2013 R, typically those types of questions i can't tell when it just states that it's released from rest...


it depends on where its held at rest, if its at rest at a point after the equilibrium extension then T>particles Weight therefore will move upwards towards equilibrium and if where its held at rest is before the equilibrium point then T<particles weight and therefore will move downwards towards equilibrium. if thats what you're asking?
(edited 6 years ago)

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