# Projectile motion with air friction

1. Jun 27, 2012

### 106267

I'm trying to understand the motion of projectile motion under the influence of air resistance. A website such as this details the necessary equations available to approximate this model: http://claymore.engineer.gvsu.edu/~michels/index_files/Golf%20Ball%20Paper%20Final%20draft.pdf [Broken]
However, i am unable to calculate vaild results.
I'm using the constant air friction equation
x(t)=(24τV cosθ)/(C_D Re) e^(-((C_D Re)/24τ)t)+(24τV cosθ)/(C_D Re)
&
y(t)=〖(V sinθ+24τg/(C_D Re))( -24τ/(C_D Re) e^(-((C_D Re)/24τ)t) )+((V sinθ+24τ/(C_D Re))(24τ/(C_D Re)))-(24τ/(C_D Re))t

Reading on the linked website will provide in detail what these variables equal.

My results are
Velocity:v=2.85ms
Angle 60 degrees
mass: 0.004kg
Diameter: 0.016m
This is all done in the fluid of air
at around 20°C

Last edited by a moderator: May 6, 2017
2. Jun 27, 2012

### Simon Bridge

In what way are these not valid results?

[aside: the link is not valid]

3. Jun 28, 2012

### 106267

Sorry what i'm meant to say is that my results are my initial values. When i sub these into the equation listed the results i obtain are invalid. Try the link again it should be vaild. If not just type into google search and click the most common url located

4. Jun 28, 2012

### Simon Bridge

However I now have the pdf linked to. Thanks.