Generating Steady-State Chain Fountains

TL;DR

This paper introduces a mechanical model to generate and explain steady-state chain fountains, providing insights into reaction forces and making the phenomenon accessible for educational purposes.

Contribution

It proposes a new illustrative mechanical system model that explains steady-state chain fountains and predicts reaction forces, enhancing understanding of this physical phenomenon.

Findings

The model can generate all physical chain fountain configurations.

It offers a complete explanation for reaction forces involved.

Simplifications make the phenomenon accessible to undergraduates.

Abstract

In recent years the chain fountain became prominent for its counter-intuitive fascinating physical behavior. Most widely known is the experiment in which a long chain leaves an elevated beaker like a fountain and falls to the ground under the influence of gravity. The observed chain fountain was precisely described and predicted by an inverted catenary in several publications. The underlying assumptions are a stationary fountain and the knowledge of the boundary conditions, the ground and beaker reaction forces. In contrast to determining the steady-state chain fountain shape, it turns out that the main difficulty lies in predicting the reaction forces. A consistent and complete physical explanation model is currently not available. In order to give a reasonable explanation for the reaction forces an illustrative mechanical system for generating steady-state chain fountain is proposed in this work. The model allows to generate all physical possible chain fountains by adjusting a pulley arrangement. The simplifications incorporated make the phenomenon accessible to undergraduate students.