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 irule
Captain
Joined: Sep 20, 2006
Member#: 2410
Posts: 1379
Location: Canada
   
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 Posted:
Mon Mar 22, 2010 10:00 pm Post subject: |
 
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I don't understand how you got πr²dh + 2πrhdr.
Here's what I did:
measured volume = (3.1415)x(10x10)x15
= 4712.25
max volume = (3.1415)x(11.2x11.2)x17.4
= 6856.81
The difference between the measured and the max is 2144.59.
So if the real volume is 6856.81, you were off by 31.27%. Why did you take the percent as fraction of the measured volume? Shouldn't it be a fraction of the volume with the highest difference?
What did I do wrong?  |
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 Stuka_Kommandant
Commodore
Joined: Jan 01, 2007
Member#: 2872
Posts: 7303
Location: St. ARDBEG, D.C. double-central Whiskyonsin
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Posted:
Mon Mar 22, 2010 10:42 pm Post subject: |
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One seems sure: This is not
definitively Dark's thread...
  
_________________
"More Whisky!" was my answer 
but i can't remember the fkn question... |
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 tr1sth3t
Lieutenant Commander
Joined: Feb 27, 2007
Member#: 3130
Posts: 279
Location: Bergen
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Posted:
Mon Mar 22, 2010 10:53 pm Post subject: |
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| irule wrote: |
I don't understand how you got πr²dh + 2πrhdr.
Here's what I did:
measured volume = (3.1415)x(10x10)x15
= 4712.25
max volume = (3.1415)x(11.2x11.2)x17.4
= 6856.81
The difference between the measured and the max is 2144.59.
So if the real volume is 6856.81, you were off by 31.27%. Why did you take the percent as fraction of the measured volume? Shouldn't it be a fraction of the volume with the highest difference?
What did I do wrong? |
First your value of pi is not precise enough causing a loss of accuracy. The value of pi is 3.141592654, using 3.14 would have been better. Or if you would have used 3.1416. I don't understand where you got the values 11.2 and 17.4.
We are also looking for the absolute error and the maximum possible relative error as a percent.
absolute error = ΔV (differentiate the equation for volume using product rule)
relative error = absolute error ÷ value of thing measured
_________________
It is more likely that a brain randomly forms out of the chaos with false memories of its life than that the universe around us would have billions of self-aware brains. |
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irule
Captain
Joined: Sep 20, 2006
Member#: 2410
Posts: 1379
Location: Canada
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Posted:
Mon Mar 22, 2010 10:58 pm Post subject: |
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11.2 and 17.4 are the max radius and height given the possible error. I don't understand why you would need any other values since these give you the greatest difference in volume.
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tr1sth3t
Lieutenant Commander
Joined: Feb 27, 2007
Member#: 3130
Posts: 279
Location: Bergen
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Posted:
Mon Mar 22, 2010 11:01 pm Post subject: |
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| irule wrote: |
| 11.2 and 17.4 are the max radius and height given the possible error. I don't understand why you would need any other values since these give you the greatest difference in volume. |
You should only use the given radius and height r = 10m & h = 15m. Then whatever measuring them has a limit of ±1.2m and ±2.4m. Any other values that are used will be incorrect. You see we are looking for the error because we have limits. If a computer can only measure ±1.2m as the radius before it starts producing incorrect results, 10m is going to fuck it up big time.
And that's the point of finding the solution(s) to this problem. To see just how wrong we/it is.
_________________
It is more likely that a brain randomly forms out of the chaos with false memories of its life than that the universe around us would have billions of self-aware brains. |
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irule
Captain
Joined: Sep 20, 2006
Member#: 2410
Posts: 1379
Location: Canada
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Posted:
Mon Mar 22, 2010 11:05 pm Post subject: |
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What I'm saying is the range of possible values is 8.8-11.2 and 12.6-17.4. If you plug in the highest values you get a possible actual volume of 6856.
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tr1sth3t
Lieutenant Commander
Joined: Feb 27, 2007
Member#: 3130
Posts: 279
Location: Bergen
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Posted:
Mon Mar 22, 2010 11:14 pm Post subject: |
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| irule wrote: |
| What I'm saying is the range of possible values is 8.8-11.2 and 12.6-17.4. If you plug in the highest values you get a possible actual volume of 6856. |
I see what you're saying and that seems logical but that isn't the case with this problem. You can simply plug the given values in to the correct equations.
Check this out too.
http://www.phy.ilstu.edu/slh/Absolute%20Relative%20Error.pdf
_________________
It is more likely that a brain randomly forms out of the chaos with false memories of its life than that the universe around us would have billions of self-aware brains. |
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irule
Captain
Joined: Sep 20, 2006
Member#: 2410
Posts: 1379
Location: Canada
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Posted:
Mon Mar 22, 2010 11:25 pm Post subject: |
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Can you explain how you got:
ΔV ≈ dV = (dπr²)
= πr²dh + hd(πr²)
= πr²dh + h2πrdr
= πr²dh + 2πrhdr
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tr1sth3t
Lieutenant Commander
Joined: Feb 27, 2007
Member#: 3130
Posts: 279
Location: Bergen
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Posted:
Sun Mar 28, 2010 2:19 am Post subject: |
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| irule wrote: |
Can you explain how you got:
ΔV ≈ dV = (dπr²)
= πr²dh + hd(πr²)
= πr²dh + h2πrdr
= πr²dh + 2πrhdr |
I used the product rule of differentiation.
_________________
It is more likely that a brain randomly forms out of the chaos with false memories of its life than that the universe around us would have billions of self-aware brains. |
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irule
Captain
Joined: Sep 20, 2006
Member#: 2410
Posts: 1379
Location: Canada
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Posted:
Sun Mar 28, 2010 1:59 pm Post subject: |
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Calculus needs to die.  |
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 SeclusionSolution 
Commodore
Joined: Jun 22, 2006
Member#: 2031
Posts: 3594
Location: Papua New Guinea
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Posted:
Sun Mar 28, 2010 2:08 pm Post subject: |
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| irule wrote: |
| Calculus needs to die. |
  sadly a lot inventions wouldn´t be possible without it
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 lunarstrain88
Captain
Joined: Dec 25, 2009
Member#: 9680
Posts: 2403
Location: Karachi, Pakistan
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Posted:
Sat Jun 19, 2010 4:33 am Post subject: |
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Last edited by lunarstrain88 on Tue Jun 22, 2010 7:40 pm; edited 2 times in total |
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Dami
Commodore
Joined: Feb 04, 2005
Member#: 87
Posts: 2567
Location: Stalag 13
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Posted:
Tue Jun 22, 2010 2:15 pm Post subject: |
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Blowhard  .
_________________
o
L_
OL
This is Schäuble. Copy Schäuble into your signature to help him on his way to Überwachungsstaat. |
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lunarstrain88
Captain
Joined: Dec 25, 2009
Member#: 9680
Posts: 2403
Location: Karachi, Pakistan
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Posted:
Tue Jun 22, 2010 8:16 pm Post subject: |
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| Dami wrote: |
| Blowhard . |
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Dark
Commodore
Joined: Jul 25, 2005
Member#: 589
Posts: 3246
Location: Ottawa, Ontario
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Posted:
Tue Jun 22, 2010 10:36 pm Post subject: |
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| Stuka_Kommandant wrote: |
One seems sure: This is not
definitively Dark's thread...
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You are correct, i refuse to use complicated mathematics unless needed or directed by a doctor.
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