Step 1:

Create a new document in Flash. You can take a look at my default document settings.








Step 2:

Select the Oval tool & make a perfect circle by holding ALT while you drag.Place that circle out of your play screen.






Step 3:

Click once on your ball and press F8 to convert shape into graphic. That step will get you better results in your animations.







Step 4:

Create a new layer & right click (CRTL+click for Mac) & select properties. Select Guide, click OK. Return to your new layer and select the the Pen tool.
You will need to draw a split-curved line. Take a look at the sample below.




Step 5:

Create a new layer & right click (CRTL+click for Mac) & select properties. This Time Select guided. Click on your ball and drag its center onto your guid line.








Step 6:

Insert Keyframe at 20 & 50 on the Ball Layer. Insert a keyframe at 50 on the guide layer.








Step 7:

Here comes the Gravity "effect". Click on the first frame of the ball layer. In you main pannel, select Tween: Motion and set the erase like mine







Step 8:

Click on the frame 20 of the ball layer. In the main pannel again, select Tween: Motion and set the erase like mine.











Step 9:

Click on the frame 50 of the ball layer & drag your ball to the end path (centered).












Your Done!




View End Result