Gravity, positive negative acceleration

programming flash
1

How to get accelerated gravity upwards after the UP-key is released:


onClipEvent(load){

_root.ymove=15;
realymove=15;
ydmove = 15;
_root.gravityplayer = 2 ;
_root.speedyplayer = 0 ;
}

onClipEvent (enterFrame){

_root.speedyplayer = _root.speedyplayer*1.0 + _root.gravityplayer ;

if (_root.speedyplayer>30){_root.speedyplayer=30}

this._y += _root.speedyplayer/5 ;

if( Key.isDown(Key.DOWN) ){_y = _y + ydmove;}
if( Key.isDown(Key.UP) ){_y = _y - _root.ymove; _root.speedyplayer = _root.speedyplayer*1.0 - _root.gravityplayer*3 ;}

if (_y<510){_root.gravityplayer = 2 ; ydmove=realymove;}
if (_y>510){_root.gravityplayer = -30 ;}
if (_y>510){_root.speedyplayer = 10; ydmove=0;}
}