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# How was Edexcel M5? watch

1. I found it pretty bad probly got around 70% .... I couldnt do the vector equation of the line of action of the force question nor the moments of inertia integration. I managed everything else and got the same answers as some mates tho....

Any of these answers ring a bell? 39J, 77/109 sumthin..., 60 degrees?
2. EZ think i got 98%....syke...
3. any body got there soultions to print, i think i got all but the integration of that equilatral triangle lamina intergration ukno 7a, i made an stupid error. but for that vector equation for the line of action of R mine was something liek 4i - k or something like that, i have the paper if anybody wants a copy btw
4. (Original post by tktaylor6)
i have the paper if anybody wants a copy btw
Yes please! I have a few solutions. The rocket car question is exactly the same as Ex2A Q7 from the book, so i got the first part (bar a fudged negative) shame i ran out of time for the second part.
The triangle integration I doubt many people will have got, I know I didn't. But the angle for that i don't think was 60° because G on an equliateral triangle is (1/√3)h from the vertex not (2/3)h correct me if i'm wrong.
39J definitely sounds right.
Any 2PI√(3a/8g) 's?
5. I thought because G is (1/√3)h horizontally from A and G is h/3 up along h from the base
then
AG squared = ((1/√3)h)^2 + (h/3)^2
AG = 2h/3....
I maybe wrong..... oh well method marks might save my ass....

ps mackin_boi are you joking cos then UMS will bring me down........
6. (Original post by herman368)
ps mackin_boi are you joking cos then UMS will bring me down........
Yeah, if you have got that many marks it's a bit harsh on the rest of us, seeing as there are only about 300 people who take this paper. good luck to you. Shall we stop worrying about that stupid triangle?
7. grrr that triangle, if i only i took my rod elements horizontally not vertically.....grrrrr

oh well i put the most longwinded answer ever muhahahahahahahaa stupid examiners..
8. (Original post by herman368)
I found it pretty bad probly got around 70% .... I couldnt do the vector equation of the line of action of the force question nor the moments of inertia integration. I managed everything else and got the same answers as some mates tho....

Any of these answers ring a bell? 39J, 77/109 sumthin..., 60 degrees?

ya i found THOSE questions to be REALLY hard, there are questions tht are easy, and others that are neither easy not hard, in general it was A LITTLE BIT hard, as those two questions are for 7 and 9 marks.

the 39J is right
77/109 I THINK it's something like that
60 degrees, mmmmmmmm i remember having a pi/3 rad somewhere so i think u r right for that too...

can anyone remember what the answers are? or questions too?
9. (Original post by yazan_l)
in general it was A LITTLE BIT hard
oh good, it wasn't just me! From your varing mass solution you seem pretty damn smart, so that's some encouragement.
10. well i got 39J also, and i used 2/3 h also dudes, ill scan this bad boy now and put it on here
11. i cant remeber which question but i think it was 4 b did anybody else get liek root with a root 2 inside that stuff beign rooted?
12. ok i dont know how to attach on this thing i have the paper so if your want a copy just add me onto msn its [email protected] and i will be happy to send it to you. also please share your answers with me after
13. (Original post by tktaylor6)
i cant remeber which question but i think it was 4 b did anybody else get liek root with a root 2 inside that stuff beign rooted?
YEAH, mate I got that...... also another guy at my school got that too!

Phew...
14. hurrah!!!
15. Did any of you get that damned vector question? I had no idea how to approach it, so I complately made some stuff up in hopes of getting a couple of method (or sympathy!) marks.

I got a 77/109 somewhere, 39J for work done, and I got a sqrt[2] inside a square root also - I believe it was for the period of the oscillations. The triangle one was definitely tricky, as there were parallel and perpendicular axes involved (took me a while to notice that).

I made a load of stupid mistakes too, e.g. 1-0.5=0.25, so my answer to the angle question was arccos(0.25) instead of arccos(0.5)=pi/3. And for the vertical component question I went and found the horizontal component. Ugh.

Also, how did you guys do the last part of the last question - the maximum angular acceleration one? I tried using , but for some reason I changed my mind and went and found the minimum tangential acceleration instead. No idea why I did that, although I like to blame exam pressure.

I feel like crap now.
16. (Original post by dvs)
Did any of you get that damned vector question?
Here's what I did, it may be right may be wrong:

xi+yj+zk x R = G

| i j k |
| x y z | = 7i-3j+8k
|-1 3 2|

equating components of i, j and k:
2y-3z = 7
-(2x+z) = -3
3x+y = 8

letting x=0 : y=8, z=3

line of action is therefore
r = 8j+3k +k(-i+3j+2k)
17. Hmm.. But why should R be parallel to G?
18. (Original post by Daft Wader)
Here's what I did, it may be right may be wrong:

xi+yj+zk x R = G

| i j k |
| x y z | = 7i-3j+8k
|-1 3 2|

equating components of i, j and k:
2y-3z = 7
-(2x+z) = -3
3x+y = 8

letting x=0 : y=8, z=3

line of action is therefore
r = 8j+3k +k(-i+3j+2k)

are you sure of this?
i mean i dont know and i hope so, coz i did all to :
2y-3z = 7
-(2x+z) = -3
3x+y = 8
and then stopped because i thought it was all wrong!!! i HOPE u are right!!! but DAMN IT, why i didnt continue!!!!
19. (Original post by Daft Wader)
oh good, it wasn't just me! From your varing mass solution you seem pretty damn smart, so that's some encouragement.

lol thanks , hehehe, cheers
20. by the way: for the pendulum period question, which should be used:
T = 2π √[I/(mgh)] OR T = 2π/w?

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