First you need to make
a round ball. Select the oval too, and make a ball of your choice. Remember
to hold down the shift key while drawing the "perfect circle".
You can use solid colors, or to make the animation fancier, you can use
a gradient.
Step 2:
Select
the ball and go to Insert > Convert to Symbol.
Name the circle whatever you please and make sure
the behavior is graphic.
Step 3:
Make three key frames,
each 10 instances apart. Each key frame should have the ball in the same
position at this point.
Step 4:
Select the tenth key frame. Now select the ball. Hold the shift key and
drag it down to the desired position
Step 5:
Select the ball at the tenth key frame and resize it. Squish it down a
little by selecting the scale option in the arrow tool.
Step 6:
Now select the 1st keyframe and go to Frame Properties
> Tweening. Select the motion tween. Now make
the easing in -100. Now select the tenth key frame and make the easing
out 100.
Step 7:
To see your animation simply press
Ctrl + Enter or Control > Test Movie. Note, you can increase the speed
of the movie in the Movie Properties menu by increasing the fps.