Maths Experts ??
56astro - May 7th, 2006 at 02:03 PM
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 - May 7th, 2006 at 03:54 PM
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 - May 7th, 2006 at 04:18 PM
i can count almost to 10 :duh
phatratpat - May 7th, 2006 at 04:23 PM
ah yes ! but how long do u cook it for ?
56astro - May 7th, 2006 at 04:36 PM
Thanks Pete
I'll give it a crack when I get home
:thumb
zac_smits - May 7th, 2006 at 06:52 PM
| Quote: |
Originally
posted by 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.
|
i got the same thing!!!
go engineering maths :P
helbus - May 7th, 2006 at 06:59 PM
My cats breath smells like catfood. :duh
modulus - May 7th, 2006 at 07:11 PM
My dogs' breath smells of cats.
Notch Nut - May 8th, 2006 at 11:29 PM
| Quote: |
Originally
posted by 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.
|
Clarity???:o Yeah...like MUD!!:P
Not just your average dumbasss
- Adam
Scarlet - May 9th, 2006 at 07:35 AM
| Quote: |
Originally
posted by Helbus
My cats breath smells like catfood. :duh
|
'I'm a todem pole...haya haya, haya haya':P
Ich fahre ein Kdf ein Tag - May 9th, 2006 at 09:46 AM
| Quote: |
Originally
posted by 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.
|
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 - May 9th, 2006 at 12:21 PM
| Quote: |
Originally
posted by Ich fahre ein Kdf ein Tag
| Quote: | Originally
posted by 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.
|
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 - May 9th, 2006 at 12:30 PM
I bent my wookie... 
56astro - May 9th, 2006 at 12:47 PM
I just admire people who "know their stuff"
:beer
PrettyBlueBug - May 9th, 2006 at 01:11 PM
Today is Tuesday. :P
Ich fahre ein Kdf ein Tag - May 9th, 2006 at 01:55 PM
| Quote: |
Originally
posted by modulus
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 - May 9th, 2006 at 03:37 PM
| Quote: |
Originally
posted by modulus
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 - May 9th, 2006 at 03:58 PM
| Quote: |
Originally
posted by Ich fahre ein Kdf ein Tag
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 - May 9th, 2006 at 04:00 PM
^^ 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 - May 9th, 2006 at 05:05 PM
HEY maths nerd you like fruit!
I got her number!
how do you like them apples?
good hunting will.
Notch Nut - May 9th, 2006 at 05:08 PM
I'll bet all of you brainiacs can program a VCR as well!:alien
- Adam:duh
4ThALaStTiMe - May 9th, 2006 at 05:25 PM
the Ultimate Answer to Life, the Universe, and Everything
Cardinal 42
forty-two
Ordinal 42nd
forty-second
Factorization 2 × 3 × 7
Divisors 2, 3, 6, 7, 14, 21
Roman numeral XLII
Binary 101010
Hexadecimal 2A
IEEE Float 42.0 = 42280000 hexadecimal
Hebrew מב (Mem Bet)
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).
http://en.wikipedia.org/wiki/The_Answer_to_Life%2C_the_Universe%2C_and_Everyt...
Notch Nut - May 9th, 2006 at 05:36 PM
| Quote: |
Originally
posted by 4ThALaStTiMe
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
zac_smits - May 9th, 2006 at 05:56 PM
crewcabconnection - May 9th, 2006 at 05:59 PM
can you google that shit?
weapon - May 9th, 2006 at 06:09 PM
thats a pretty triangle.
amazeer - May 9th, 2006 at 06:49 PM
12Beer + EarlyMorningKebab = Trouble
koolkarmakombi - May 9th, 2006 at 07:21 PM
PMSL :P
| Quote: |
Originally
posted by amazeer
12Beer + EarlyMorningKebab = Trouble
|
MickH - May 9th, 2006 at 07:32 PM
| Quote: |
Originally
posted by 4ThALaStTiMe
the Ultimate Answer to Life, the Universe, and Everything
Cardinal 42
forty-two
Ordinal 42nd
forty-second
Factorization 2 × 3 × 7
Divisors 2, 3, 6, 7, 14, 21
Roman numeral XLII
Binary 101010
Hexadecimal 2A
IEEE Float 42.0 = 42280000 hexadecimal
Hebrew מב (Mem Bet)
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).
http://en.wikipedia.org/wiki/The_Answer_to_Life%2C_the_Universe%2C_and_Everyt...
|
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 - May 9th, 2006 at 08:48 PM
| Quote: |
Originally
posted by 4ThALaStTiMe
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