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 11-28-06, 10:39 PM #1 phantomcow2 la vache fantôme Thread Starter     Join Date: Aug 2004 Location: NH Bikes: Posts: 6,266 Mentioned: 0 Post(s) Tagged: 0 Thread(s) Quoted: 1 Post(s) Include air resistance in your calculations? In my physics class, all of our problems dealing with any type of motion say "neglecting air resistance" as a footnote. I was just wondering, what does a sample calculation look like when you don't neglect air resistance for a flying object? I don't know if he tells us to do this because it is either something we have not studied yet but will, or something he was not planning to cover because it is fairly advanced. I am just curious about what a sample calculation would look like __________________ C://dos C://dos.run run.dos.run
11-28-06, 10:43 PM   #2
Tom Stormcrowe
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 Originally Posted by phantomcow2 In my physics class, all of our problems dealing with any type of motion say "neglecting air resistance" as a footnote. I was just wondering, what does a sample calculation look like when you don't neglect air resistance for a flying object? I don't know if he tells us to do this because it is either something we have not studied yet but will, or something he was not planning to cover because it is fairly advanced. I am just curious about what a sample calculation would look like
Here's a bike speed and power calculator site that also has an excellent tutorial on the math included. It takes into account air resistance AND density as well as wind speed and direction, ie: head or tail.
http://www.kreuzotter.de/english/espeed.htm
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 11-28-06, 10:48 PM #3 slvoid 2-Cyl, 1/2 HP @ 90 RPM     Join Date: Oct 2003 Location: NYC Bikes: 04' Specialized Hardrock Sport, 03' Giant OCR2 (SOLD!), 04' Litespeed Firenze, 04' Giant OCR Touring, 07' Specialized Langster Comp Posts: 15,762 Mentioned: 0 Post(s) Tagged: 0 Thread(s) Quoted: 4 Post(s) Just add 1/2cpav^2.
11-28-06, 11:40 PM   #4
DannoXYZ
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 Originally Posted by slvoid Just add 1/2cpav^2.
That's like someone buying a Haynes manual to work on their car. Then flipping to the section on changing the timing-belt and the first step says, "Remove Engine"...

11-28-06, 11:47 PM   #5
HereNT

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 Originally Posted by DannoXYZ That's like someone buying a Haynes manual to work on their car. Then flipping to the section on changing the timing-belt and the first step says, "Remove Engine"...
If it were a wiki and that first step was a link to steps for removing engines on different models of cars...

 11-29-06, 05:14 AM #6 j-dowsett Senior Member   Join Date: May 2005 Location: Salisbury, UK Bikes: Decathlon R 7.4 Posts: 55 Mentioned: 0 Post(s) Tagged: 0 Thread(s) Quoted: 0 Post(s) Including a term in air resistance complicates the mathematics significantly. Taking freefall under gravity as an example, without air resistance the acceleration is constant, and can be integrated once or twice (as required) to give speed or position with respect to time. Including air resistance, the acceleration now has an extra term, not simply in v, but in v^2. So you've now a second order non-linear differential equation that in many situations will not be possible to solve explicitly.
11-29-06, 06:23 AM   #7
slvoid
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 Originally Posted by DannoXYZ That's like someone buying a Haynes manual to work on their car. Then flipping to the section on changing the timing-belt and the first step says, "Remove Engine"...
Do you want to give this kid ALL the answers?

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