Wind Resistance

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Caleb - 10 Apr 2007 01:37 GMT

Hello everybody. I'm doing my final project for my AP Java class and
I was wondering if anybody had any suggestions on how to use air
resistance. I really don't have any idea what to do to use air
resistance in my program, but it's required. My program is going to
involve dropping a ball if that helps any. The most luck I've had has
been from Googling stuff on air resistance Java source code. Any help
would be appreciated, thanks.

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Brandon McCombs - 10 Apr 2007 02:04 GMT

> Hello everybody. I'm doing my final project for my AP Java class and
> I was wondering if anybody had any suggestions on how to use air
[quoted text clipped - 3 lines]
> been from Googling stuff on air resistance Java source code. Any help
> would be appreciated, thanks.

This has nothing to do with any language until you run into a problem
during implementation. Don't do your searches based on keywords of java
and air resistance because you would be limiting yourself too much,
unless you plan on copying the java code. That is because at this stage
the language you use is mainly irrelevant.

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Hal Rosser - 10 Apr 2007 02:06 GMT

Try googling "drag coefficient" instead of wind resistance.
a ball has a certain coefficient of drag and if its 'falling' you have
gravity pulling down and resistance to falling (drag).
at some point, the ball could possibly reach 'terminal velocity'.
--assuming you drop the ball where air is present - as opposed to on the
moon,
sounds like a fun project

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Joshua Cranmer - 10 Apr 2007 02:43 GMT

Having taken physics recently, I remember that Fair = -A*b*v^n where A
is the cross-section area of the object (pi*R^2 for a spherical ball), b
is a constant related to the air, and n is 1 for low velocity and 2 for
high velocity.

Hope this helps.

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Andrew Thompson - 10 Apr 2007 03:45 GMT

>I was wondering if anybody had any suggestions on how to use air
>resistance.

This application simulates it.
<http://www.1point1c.org/spacesim/sim/app.html>
It is open source, see the spacecim.zip available here..
<http://www.1point1c.org/spacesim/sim/>

Note that it also simulates a lot of other things, and
was never meant as a simple example of how to
code air resistance, but then you say you are in your
final year, so you should be able to figure it out.

HTH

Signature

Andrew Thompson
http://www.athompson.info/andrew/

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Alan Krueger - 10 Apr 2007 06:55 GMT

http://en.wikipedia.org/wiki/Drag_(physics)

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MS - 10 Apr 2007 16:17 GMT

Caleb emailed this:

It sounds pretty straight forward to me.

You have your rate of descent, 9.8 m/s/s. In your program have a variable
which holds the value of the speed as it increases, and another variable
which holds the value of the calculation as to how much air resistance
reduces that speed. Subtract the air resistance from the speed and that's it.

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Christian - 10 Apr 2007 16:27 GMT

MS schrieb:

> Caleb emailed this:
>> Hello everybody. I'm doing my final project for my AP Java class and
[quoted text clipped - 12 lines]
> resistance reduces that speed. Subtract the air resistance from the
> speed and that's it.

or use Lagrange's equations ... if you are good with maths that may look
nice in the end...
the resistance of the Air is just a term draining from the total Energy
of your System..
that would have the benefit that some other things could later be more
easily implemented .. and you would learn some more basics about
Theoretical Physics

Christian

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Wind Resistance

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