Accelerating object air resistance

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Discussion Overview

The discussion revolves around calculating the coefficient of air resistance for an object in motion, considering both scenarios with and without air resistance. Participants explore methods for determining this coefficient, including theoretical and experimental approaches.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant asks how to calculate the coefficient of air resistance given distances traveled with and without air resistance, along with the object's acceleration.
  • Another participant suggests that for simple shapes, coefficients can be found online, but for complex shapes, experimental methods or advanced physics simulations may be necessary.
  • A follow-up question asks if the initial launch angle or speed is known, proposing that a simulation could help predict the projectile's range for various coefficients of air resistance.
  • A participant introduces the concept of two classifications of air drag—Stokes Law drag and turbulent drag—indicating that the type of drag depends on the Reynolds number, with turbulent drag being more common for projectiles.

Areas of Agreement / Disagreement

Participants express differing views on the methods for calculating the coefficient of air resistance, with no consensus on a definitive approach. Some suggest theoretical methods while others advocate for experimental or simulation-based approaches.

Contextual Notes

There are limitations regarding the assumptions made about the shape of the object and the conditions under which air resistance is measured. The discussion does not resolve the complexities involved in determining the coefficient of air resistance for various scenarios.

ojsimon
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Ok so i have the distance traveled of an object assuming air ressistance is 0 and the distance traveled with air resistance included as well as the acceleration of the object, how would i calculate the coefficient of air resistance?


Thanks
 
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If it's a simple shape you can find it on the internet, such as this chart:

200px-14ilf1l.svg.png


But if it's something more complex...which is pretty much anything, I don't think you can figure it out using paper and a pencil. Either through experiment, or maybe with some powerful physics program.
 
ojsimon said:
Ok so i have the distance traveled of an object assuming air ressistance is 0 and the distance traveled with air resistance included as well as the acceleration of the object, how would i calculate the coefficient of air resistance?


Thanks

Do you also know the initial launch angle or launch speed? If so, you can write a simulation program that predicts the projectile's range for different coefficients of air resistance, then see which one is the closest.
 
There are two classifications of air drag; Stokes Law drag or turbulent drag, depending on whether the Reynolds number Re is below or above about Re ~1000. See

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

The air drag for projectiles is usually turbulent, and the power loss (energy loss rate) is proportional to velocity cubed (see above url).

Bob S
 
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