For the pendulum animation, maybe on its first return you could remove a bit more energy because right now it almost looks like there's no loss of energy there and (though I'm not very strong in physics) I think the loss of energy in a pendulum is consistent?
It's been a while since I animated so I thought I'd give this a shot (nobody's posted in my unrust thread yet ;-; )

Bouncing Ball - No Decay
http://sta.sh/010c3z83fztm

Bouncing Ball - No Decay (TWEEN)
http://sta.sh/0ttw0jz7eka