Add getR() method to ball.
Just *in case* we need it for collision detection. You know.
Set fill value of ellipse around Cage to black.
Fix bug where ball goes below ground.
If velocity was too large, it would go below the ground. Now, automatically set the y value to height.
Slow animation down.
Change values for gravity and velocity. These will be changed back eventually.
Format output of ball's position.
Calculate and print time.