The following is a neat little experiment, the result of which may be counter-intuitive to some of those who embrace the “all bodies fall the same way inside earth’s gravity” doctrine.

Remember, in ages long ago people thought that a feather does not fall as fast as a cannon ball. Nowadays, people are so much smarter, at least they feel so much smarter, and they know that the feather only falls slower due to air resistance. This has become somewhat of a doctrine in the sense that many do not really understand the underlying reasons. They are surprised by the nifty little experiment in the linked video: The wooden angle reaches the table long before the ball does, not only because they start out a little different, but also because the tip of the plank accelerates faster than the freely falling ball (See the golf tee? It Immediately separates from the ball and speeds downward, leaving the ball behind.).

It is a simple set-up and a good idea for a project that can involve children. Older ones may be able to calculate the required lengths of the wooden angle's arms. If the video should not be embedded correctly, you may have to surf to it on the MIT website.

And here is the new 'didactic challenge': Who comes up with the shortest and most philosophical reason for why the ball ends up in the cup?

CLARIFICATION: I am not interested in why the ball is in the cup but in the fact that the end of the arm accelerates more than the free falling ball although much of the force onto the wooden plank just presses on the joint (hinge). (This is necessary for the ball to land in the cup, so I formulated the question above that way, which has misled some readers. Sorry about that. This is really about that the tip accelerates faster, as is proven by the tee separating from the ball at once without dragging it to the side. Moreover, at larger starting angles, all this would not happen!)