In the following steps,
you set a playback range that’s long enough to see the animation
clearly. You also create the ball and the door, and position them in
the scene view in preparation for the animation.
Scale and position it roughly as shown
in the previous figure. Have the bottom edge of the door lie roughly
along the X-axis.
With the pointer in the perspective view,
press 5 (for Shading > Smooth Shade All).
Create a small polygonal sphere and name
it Ball. Scale and
position it roughly as shown in the prior figure in the introduction.
Have it sit roughly at 0, 1, 10 (X, Y, Z).