M3 Pre-Exam thread (edexcel)

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As i just stated all the proofs apart from hemispherical shells are required and this one is a cracker i have to say as its harder than the hemispherical shell in my opinion but you just have to grind through x(a-x^2)^0.5 calculations im affraid! sorry to put a downer before the exam

May I ask where you're getting the information that all the proofs are required apart from hemispherical shells? I'm using the older M3 book, and, regarding the rsinx/x proof, there's a little box at the bottom of the page saying "Note: This result is given in the formula sheet. You will not be expected to reproduce this proof in your M3 exam."

Reply 141

physics1

Original post by Zhy

when you say rsinx/x proof is that proof by first principles? you never have to use that but calculus you do have to use. I have seen past papers about triangular laminas, solid cones, solid hemispheres

Reply 142

Kaiser7

I've just looked through the M3 syllabus. It doesn't say we need to be able to prove anything in chapter 5... not even the sector c.o.m formula proof, which the book says needs to be known. So, now I'm confused. :s-smilie:

Reply 143

Zhy

Original post by physics1

Yes. Where have you seen the past paper questions asking you about finding the centres of mass of triangular laminae and solid hemispheres via integration? I did every past paper going back to June 2001 and I don't remember doing that...? I agree with the solid cone proof as that's come up in an official paper (and in a Solomon paper) but not the other two.

Reply 144

physics1

Original post by Kaiser7

yes i have just checked too and i would agree with you looking at that! But i mean they do like to dabble in harder stuff not technically in the syllabus. However being able to find integrals of shapes from graphs is in the syllabus so proofs using this technique is therefore in the syllabus

Reply 145

physics1

Original post by Zhy

ok revision exercise 2 q38 for poof of triangular lamina, q36 for semi circular lamina, q50 for right circular cone and q48 for the solid hemisphere. All of these have been taken from past papers

Reply 146

Laurence94

Original post by dzone25

I REALLY need M3 and C3 but geog today has left me feeling like poop and not to mention the horrible physics on monday =[

Just want this week over so I have a few days for Physics, geog, FP2 and C4 next week

touch wood I scrape 90+ in C3 and something decent in M3 =[

Sounds like we do the same subjects, lol! Fortunately already got 90+ in C3, so although I am re-doing it, it's not the most important of exams! M3, than PHYA5 on Monday, on the other hand, not to mention FP3 which I have no clue on most of it currently! :smile:

Reply 147

skrail

Original post by King_Arthur

meeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeee :smile:

damn it why do i sound happy :eek:

Lol, I'm strangely confident, maybe the fact that I'm doing m3 hasn't yet sunk in! Guess your doing s3 c4 double next week, slowly followed by fp2?

This was posted from The Student Room's iPhone/iPad App

Reply 148

sweetascandy

Original post by natninja

I don't think you understand how the A* works, you have to average 90+ in your BEST THREE A2 modules rather than all of them so if you say get 100UMS in FP2 and S2 you still need 70UMS in M3 so don't just give up. Best of luck to everyone :smile:

also, the questions in the textbook are not all very good and are generally much more difficult than real questions

Yes I actually fully understand how the A* works :p:

I've got 100UMS in m2 and fp2. So that means I need 280 UMS in the other 4 modules to get an A, with 2 modules with 85+ for an A* (85+85+100=270=average of 90+ for 3 modules), and the other 2 with at least 55 (as 100+100+85+85+55+55=480=average for an A).
Hence, I said that if I get 85 in my 3rd module, then I will only need 25 in my 4th. do the math. :redface:

Point proven? :p:

Anyway, good luck to you :smile:

Original post by King_Arthur

go do an M1 paper

Thanks for the lovely insult but I'll have you know I got 100 in both m1 and m2 - everyone has their difficult modules, and for me that is m3 :bawling:

I'm gunna need a hell of a lot of energy drinks and coffee. The night is still young. :biggrin:

Good luck y'all! xD

Reply 149

TheMagicMan

Good luck everyone tomorrow! Hope you get what you need

Reply 150

TenaciousMonkey

In the June 2009 paper, question 5 - how do we deduce from the question that the angle swept through by the string is arccos(1/4) on one side and 60 degrees on the other side (taken from the mark scheme)? Could the question be done by only considering the motion from when it's released to the moment it passed vertically underneath the centre of the circle?

Reply 151

beardstroker

If anyone has the old M3 book (orange), please can you do question 3 in the examination style paper at the back and see if you get u=0.27?! I'm sure I've made no mistake but the answer says u=0.43.

Also if a light extensible string with a particle of 3kg attached is being dropped from a fixed point, O, vertically, when will it be at it's greatest speed? The natural length is 2m.

Many thanks in advance for any help!

Reply 152

sweetascandy

Okay well I'm now in a much better position than I was in 6 hours ago, having spent the whole night revising. Still not breezing through it, but heck it's m3! The exam is in 4 hours so I should get at least 2 hours sleep! D:

One last minute question though: when do you put the answer in radians and when in degrees? In the x=asinwt, I think thats radians, whereas slope questions are in degrees. Can someone confirm this? :redface:

Reply 153

King_Arthur

Original post by sweetascandy

I do any ALL SHM in raidans
and other questions i do it what ever form the data is given

Reply 154

dzone25

Good luck everyone, I've realised if you simply concentrate question by question its not THAT hard of a paper. Just calm down and we'll all do well on what is likely going to be a hard paper :3

Reply 155

dzone25

Sorry for double posting (on my phone) but here's a quick tip.

Don't give up on angles, every time in vertical circles I give up on the angle (when its for eg a projectile flying off at theta) you can always use basic angle rules like the good ol' Z angle :biggrin:

It also helps with toppling/sliding and when there's something on a bend