I am having trouble working on an equation. The equation is "leicesters Model for determining radiant heat flux:
Qd = 60 x (1 - exp(-I / 3000x df))
How should the equation be written when trying to determine df:
df = ??
Can anyone help?
modulus ·
Qd = 60 * (1 - exp(_I/3000*df)
exp(_I/3000*df) = 1 - Qd/60
-I/3000*df = ln(1 - Qd/60)
3000*df = -I / (ln(1 - Qd/60))
df = -I / (ln(1-Qd/60) */ 3000)
I've used more parentheses than striclty necessary for clarity.
hth.
fekkinell ·
i can count almost to 10 :duh
phatratpat ·
🤓ah yes ! but how long do u cook it for ?😀
56astro ·
Thanks Pete
I'll give it a crack when I get home
:thumb
zac_smits ·
modulus wrote:Qd = 60 * (1 - exp(_I/3000*df)
exp(_I/3000*df) = 1 - Qd/60
-I/3000*df = ln(1 - Qd/60)
3000*df = -I / (ln(1 - Qd/60))
df = -I / (ln(1-Qd/60) */ 3000)
I've used more parentheses than striclty necessary for clarity.
hth.
i got the same thing!!!
go engineering maths :P
helbus ·
My cats breath smells like catfood. :duh
modulus ·
My dogs' breath smells of cats.
Notch Nut ·
modulus wrote:Qd = 60 * (1 - exp(_I/3000*df)
exp(_I/3000*df) = 1 - Qd/60
-I/3000*df = ln(1 - Qd/60)
3000*df = -I / (ln(1 - Qd/60))
df = -I / (ln(1-Qd/60) */ 3000)
I've used more parentheses than striclty necessary for clarity.
hth.
Clarity???:o Yeah...like MUD!!:P
Not just your average dumbasss
- Adam
Scarlet ·
Helbus wrote:My cats breath smells like catfood. :duh
'I'm a todem pole...haya haya, haya haya':P
Ich fahre ein Kdf ein Tag ·
modulus wrote:Qd = 60 * (1 - exp(_I/3000*df)
exp(_I/3000*df) = 1 - Qd/60
-I/3000*df = ln(1 - Qd/60)
3000*df = -I / (ln(1 - Qd/60))
df = -I / (ln(1-Qd/60) */ 3000)
I've used more parentheses than striclty necessary for clarity.
hth.
I get similar, but i reckon this is less confusing.
From third last line:
-I/3000*df = ln(1 - Qd/60) multiply both sides by 3000/-I
1/df=((3000*ln(1-Qd/60))/-I)
df=1/((3000*ln(1-Qd/60))/-I)
Battle of the nerds 🤓, engineering maths is fun.
H
modulus ·
Ich fahre ein Kdf ein Tag wrote:
modulus wrote:Qd = 60 * (1 - exp(_I/3000*df)
exp(_I/3000*df) = 1 - Qd/60
-I/3000*df = ln(1 - Qd/60)
3000*df = -I / (ln(1 - Qd/60))
df = -I / (ln(1-Qd/60) */ 3000)
I've used more parentheses than striclty necessary for clarity.
hth.
I get similar, but i reckon this is less confusing.
From third last line:
-I/3000*df = ln(1 - Qd/60) multiply both sides by 3000/-I
1/df=((3000*ln(1-Qd/60))/-I)
df=1/((3000*ln(1-Qd/60))/-I)
Battle of the nerds 🤓, engineering maths is fun.
H
Confusion is in the mind of the beholder, grasshopper.
Whilst they both give the same answer (ain't maths wonderful!), yours is in the form of:
x = 1/A/B
which to me looks like an unnecessary inverse. What's wrong with
x = B/A ?
Dasdubber ·
I bent my wookie... 🙁
56astro ·
I just admire people who "know their stuff"
🤓
:beer
PrettyBlueBug ·
Today is Tuesday. :P
Ich fahre ein Kdf ein Tag ·
modulus wrote:Confusion is in the mind of the beholder, grasshopper.
Whilst they both give the same answer (ain't maths wonderful!), yours is in the form of:
x = 1/A/B
which to me looks like an unnecessary inverse. What's wrong with
x = B/A ?
Lol, yes but i just prefer the inverse cos it looks nicer 1/(A/B). I am fond of brackets, the more the merrier!
Craig Torrens ·
modulus wrote:My dogs' breath smells of cats.
My wife's husbands breath smells of pussy :o
[ Edited on 9-5-2006 by Craig Torrens ]
Baja Wes ·
Ich fahre ein Kdf ein Tag wrote:Lol, yes but i just prefer the inverse cos it looks nicer 1/(A/B). I am fond of brackets, the more the merrier!
why don't you just write x=(A/B)^-1 to really be confusing.
zac_smits ·
^^ and when did x come into it?? i see no x :P:P
but yeh..i love writing powers too :P
like msec^1 heheh
:P
LUFTMEISTER ·
HEY maths nerd you like fruit!
I got her number!
how do you like them apples?
good hunting will.
Notch Nut ·
I'll bet all of you brainiacs can program a VCR as well!:alien
- Adam:duh
4ThALaStTiMe ·
the Ultimate Answer to Life, the Universe, and Everything
Bracketed by twin primes, this composite number's factorization makes it a sphenic number, as it is the product of the first three terms of Sylvester's sequence. It is also the third 15-gonal number, a Catalan number, a meandric number, an open meandric number. It is believed to be the third moment of the Riemann zeta function, based partially upon evidence from quantum mechanics.
In base 10, it is a Harshad number and a self number.
It is also a perfect score on the USA Math Olympiad (USAMO) and International Mathematical Olympiad (IMO).
4ThALaStTiMe wrote:the Ultimate Answer to Life, the Universe, and Everything
:
:thumbLaughed me butt off!!!. I love the way that a fictional sci fi series can keep boffins guessing and trying to find ways of justifying if it can be made to be true. Sounds an awful lot like Scientology!!😂
- Adam
Bracketed by twin primes, this composite number's factorization makes it a sphenic number, as it is the product of the first three terms of Sylvester's sequence. It is also the third 15-gonal number, a Catalan number, a meandric number, an open meandric number. It is believed to be the third moment of the Riemann zeta function, based partially upon evidence from quantum mechanics.
In base 10, it is a Harshad number and a self number.
It is also a perfect score on the USA Math Olympiad (USAMO) and International Mathematical Olympiad (IMO).
What eva happened to "seven sixes are forty two" I might not be too smart but i can pick up heavy things🤓 (say it as though you were Cletus,the slack jawed yokel):jesus
Baja Wes ·
4ThALaStTiMe wrote:It is also a perfect score on the USA Math Olympiad (USAMO) and International Mathematical Olympiad (IMO).
I've actually got a highest individual score trophy from a Mathematical Olympiad 🤓
why did I tell people that.... :duh
type_one ·
Yes but how old were when you won it? LOL:P
$2.63 homebrand baja ·
😂🤓
what a lovely thread! what can I say, some peeps do drugs, others do maths... whilst I don't do drugs, I have to admit in yr 11 I suddenly decided I did NOT like maths, I made it my mission to go from high acheivemnt in advanced maths to vegie maths. Strategy involved sitting in class reading far side comics, writing complete nonsense in tests and embracing the low achievement status, anything above 5/100 was dissaponting to say the least... only too 6 months, several 'talks' with teachers, parents and the support of friends I did it! Whoohoo, and look at me now,,, :duh I like bunnies much more than maths. 😏
$2.63 homebrand baja ·
mmm i speel gud too 👍
Baja Wes ·
type_one wrote:Yes but how old were when you won it? LOL:P
year 7 - 12yrs old 😀
I got certificates every other year. Only got the trophy once.
I did get the Math C subject prize in year 12 though 🤓
hmmm, I think someone who can lift heavy stuff might give me a wedgy soon....
koolkarmakombi ·
(putting on Nelson type nasal whine)
haaa haaaaaaaa
Baja Wes wrote:
type_one wrote:Yes but how old were when you won it? LOL:P
year 7 - 12yrs old 😀
I got certificates every other year. Only got the trophy once.
I did get the Math C subject prize in year 12 though 🤓
hmmm, I think someone who can lift heavy stuff might give me a wedgy soon....
oval TOFU ·
Sleep! That's where I'm a viking!
zzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzz
I got a certificate of Credit for the Westpac Maths Competition once.... in Yr8 or something... alll the other times where Participation (read: douche bag) Certificates... I enjoyed yr12 pysics though, not that I remember any of it now... anyone for a kinematic equation or two?