# Accelerating object air resistance

1. Jan 31, 2010

### ojsimon

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

Thanks

2. Jan 31, 2010

### Lsos

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

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.

3. Jan 31, 2010

### ideasrule

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.

4. Feb 1, 2010

### Bob S

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 [Broken])

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

Last edited by a moderator: May 4, 2017