Uphill with Timing
How far can you bring the ball toward you?
With the right rhythm, the ball appears to roll uphill. This exhibit vividly demonstrates the interplay of energy, motion, and timing.
The Science Behind It
When the rods are parallel, the ball rests on top and rolls downhill, away from you, from the higher point to the lower one. If you pull the rods apart, the ball sinks between them. This shifts its center of gravity, causing it to start rolling toward you. It also gains speed. If you push the rods back together at just the right moment, you lift the ball, working against gravity. However, the momentum it has built up keeps it rolling toward you. Timing is the key: build up momentum first, then lift. This lets you use motion and energy to make the ball appear to move against gravity.
