mechanics plz help. (1 Viewer)

[SeDaTeD]

You might have to clarify with a teacher about that. They can't penalise you for learning more maths, but you have to justify your steps. Oh and l'hopital's rule can be used only when lim x->a f(x) and lim x->a g(x) both approach zero, or both approach infinity, and the limits of f'(x) and g'(x) exist. You have to be careful there.

 

[FinalFantasy]

ooer ok
123456789

 

[who_loves_maths]

Originally Posted by Sedated
With the conservation of energy arguement, although valid, you'd be introducing theory from physics not covered in the 4u course. The relations between force, work and energy etc are laws of physics, beyond what 4u expects you to know. So I don't think you should be using energy arguements in 4u.

However using things from uni maths such as l'hopital's rule, as long as u explain it (or prove? someone clarify), should be fine.

aww... now that's just not fair... using year 11 physics isn't allowed while uni maths is... ;

hehe... but it's fun to sometimes think "outside the square" so to speak, that was the reason i posted the conservation of energy solution, just to show maths isn't always implicit.

 

[who_loves_maths]

oh and hey FinalFantasy, have you tried/seen my question in the 3u forum yet? i just posted it... it's an interesting question to think about...

 

[SeDaTeD]

Oh, it's perfectly fine and I agree with it. Just that I don't think you'd be allowed to do it in a 4u test.

 

[FinalFantasy]

oh and hey FinalFantasy, have you tried/seen my question in the 3u forum yet? i just posted it... it's an interesting question to think about...

yea i saw it but it doesn't look like something i can do in a sec and i am currently in the middle of doing a past paper lol

 

[who_loves_maths]

Originally Posted by Sedated
Oh, it's perfectly fine and I agree with it. Just that I don't think you'd be allowed to do it in a 4u test.

^ yeah i know, you'd get a big fat 0 in a maths test if you use physics... that's too bad.

 

[who_loves_maths]

Originally Posted by FinalFantasy
yea i saw it but it doesn't look like something i can do in a sec and i am currently in the middle of doing a past paper lol

lol, doing a maths past paper at midnight? and at the same time, answering every latest post on BOS too? wow, i wish i was that skillful at multi-tasking

 

[FinalFantasy]

hahaha, im doing all these other things dats y i took half an hr and still on q2 of a 3unit paper, and i actually started like an hr ago.. but i kept bumming around and didn't really start til half an hr ago

edit: o and also it's not midnite yet

 

[who_loves_maths]

^ lol, skip straight to the last question; as if you'll be troubled by 3u stuff

 

[FinalFantasy]

man in every 3u test i do, i make about 9 marks worth of stupid things(and it's only out of 40), dis happend in all 3 MX1 assessments i've done so far
i really dun like dat and want dis error gone, so gota try and do every q

edit: and i do often get troubled by 3unit stuff, especially probability
it is a pain!

edit again: omg im still on da same q. cuz of all dis chatting lol

 

[who_loves_maths]

^ lol, better get back to it then and concentrate. i suppose vigilance and memory of where you make, or are most likely to make, silly mistakes is the best barrier and defense against making them the next time... and if you can finish an exam with spare time left for double-checking then that'll be an added bonus too.

 

[FinalFantasy]

^ lol, better get back to it then and concentrate. i suppose vigilance and memory of where you make, or are most likely to make, silly mistakes is the best barrier and defense against making them the next time... and if you can finish an exam with spare time left for double-checking then that'll be an added bonus too.

i always get time in 3u to double check but i am just an idiot, always approx 9 mistakes NO MATTER WAT LoL

edit: but not always a complete "double check", like a few mins of quick skim through some times

 

[who_loves_maths]

Originally Posted by FinalFantasy
i always get time in 3u to double check but i am just an idiot, always approx 9 mistakes NO MATTER WAT LoL

wow, that's uncanny. but don't be so self-deprecating on yourself, someone who can do hard integration questions as if they're just lifting a finger is certainly no "idiot".

 

[FinalFantasy]

wow, that's uncanny. but don't be so self-deprecating on yourself, someone who can do hard integration questions as if they're just lifting a finger is certainly no "idiot".

btw i changed the "always" to "usually" cuz i remember a time where i only had a min left..

plz stop saying as if im so good at integration! there are heaps of others including urself who can do integration easily, i bet there are some ppl who just don't say anything here but are really high lvl.. and also integration is like question 1 of the 4unit paper so not much use to be able to do hard integration q's lol

 

[who_loves_maths]

plz stop saying as if im so good at integration! there are heaps of others including urself who can do integration easily, i bet there are some ppl who just don't say anything here but are really high lvl.. and also integration is like question 1 of the 4unit paper so not much use to be able to do hard integration q's lol

well i just find your efficiency and speed at doing all the integration questions posted on this BOS forum quite exceptional...srsli.
you'd be THE best integrator if you were at my school trust me... and my school isn't a bad one either (no, it's not James Ruse )...

 

[FinalFantasy]

grrr it doesn't mean anything if i can do it fast, i am just a fast typer(u'll find me on yahoo word racer if u play it)......

 

[FinalFantasy]

if u wana c true efficiency...
look at http://www.boredofstudies.org/community/showthread.php?t=71179
Mr Ngai's super move there amazed me!

 

[who_loves_maths]

^ actually, the 'nimbleness' of one's fingers can be read as a precursor to the agility of his mind (in some cases, not all). it's like comparing a lazy person to a diligent one...

 

[who_loves_maths]

Originally Posted by ngai
let I = ∫ ln(1 +tanx) dx {between 0 and π/4}
ln(1+tanx) = -ln(1/(1+tanx) = -[ln(2/2(1+tanx))]
which gives ln(1+tanx) = -ln(2/(1+tanx)) + ln2 (log rules)
so integrate both sides from 0 to pi/4
I = -I + integral of ln2 from 0 to pi/4
2I = 1/2 int of ln2
= 1/2 ln2 (pi/4 - 0)
= pi/8 ln2

you mean this one by ngai? yea it's pretty ingenius, but srsli though, it's not really out of the blue - the first part of the question lead you into it anyways.
and with all due respect to ngai and without any sense of haughtiness, i can say that i probably would have done the same thing in the exam here... and i'm sure you can too if you give it proper thought under exam conditions.