title: perfectly elastic collisions in sprite kit
body: <p>I have two balls of equal mass that hit each other straight on.  I can't seem to figure out why there is a rebound effect on the incoming ball.  I am using sprite kit.</p>
  
  <p>I thought it was the restitution property.  I have it set to 1 (which is what I thought it should be), but have tried many.</p>
  
  <p>The only way I can kill the rebound is to change the mass, which messes up other things.</p>
  
  <p>If the speed is slow it pretty much stops as it should.  But at higher speeds there is a bounce back.   They should just exchange velocity as it is a head on collision.  Is it possibly some numerical rounding at high speeds or something?</p>
  
  <p><a href="http://h2physics.org/?cat=4" rel="nofollow">http://h2physics.org/?cat=4</a></p>