Need help with some 'advanced keyboard movement'

Hi

I’m starting a new game where the user
rides a jetski through the water, dodges
stuff and shoots enemies along the way
(based around a 007-style theme).

What I need is some help coding the movement
of the jetski (left and right). All I can do is
this:

[AS]onEnterFrame = function() {
if (Key.isDown(Key.RIGHT)) {
jetski._x += 10;
}
}[/AS]
(and do the same for ‘left’, of course)

As you can see its very basic and will
only make very ‘linear’ movement. What
I need is to sort-of ‘ease’ the motion of
the jetski. Like ‘skidding’ a little bit.

I think it’s a mathematical thing…
Quadratics? :puzzle:

Please help! :beam:

Thanks in advance.