You push the three balls as high as possible and drop them at the same time.
If you drop the balls at the same time, they reach the ground together and then fly up again. The small and middle balls will fly very high on the bar, although you would expect them to stay. Why do the two balls fly so far up?
Further informationson the exhibit "Pulse Catapult"
All objects that move are described as "impulses". This depends on the size and weight of the body. If we now drop the three balls to the ground, an impulse is transferred into the large ball. This then passes the impulse on to the middle ball and that again to the small ball. This is then catapulted upwards, because it cannot pass the impulse on to another ball.