# Friction equations?

**URL:** <https://forum.kirupa.com/t/friction-equations/243759>\
**Category:** flash\
**Created:** [November 10, 2007, 2:50pm UTC](https://forum.kirupa.com/t/friction-equations/243759 "2007-11-10T14:50:19Z")\
**Posts on this page:** 1\
**Page:** 1

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**Author:** ![duncanhall](https://avatars.discourse-cdn.com/v4/letter/d/ad7895/32.png) [@duncanhall](https://forum.kirupa.com/u/duncanhall)\
**Post date:** [November 10, 2007, 2:50pm UTC](https://forum.kirupa.com/t/friction-equations/243759/1 "2007-11-10T14:50:19Z")

</div>

I have a billiard ball system, whic detects collisions between balls and modifies their x and y velocities accordingly.

I have included a friction variable and I have a very basic system for applying the force of friction for each iteration of movement:

[AS]  
private static var FRICTION:Number = 0.94;

…  
…

public function move() : Void  
{  
mc.\_x += vx;  
mc.\_y += vy;

```
vx *= FRICTION;
vy *= FRICTION;

```

}

[/AS]

This works to a reasonable level of satisfaction, but it doesn’t quite feel right. The balls seem to take just a little too long to stop when they’ve slowed down to a very small velocity. I’ve tried tweaking the friction constasnt, but I still can’t get sometthing that feels exactly right.

Can anyone enlighten me on a more effective method to account for friction when moving balls across a given surface?