Chain Fountain

The chain rises above the cup before falling. Ask students to predict what will happen. Pull a short chain end over the rim and let it fall. Key idea: Accelerating links create an upward reaction plus momentum transfer. Ask: Why does the chain go up before gravity pulls it down? Safety and cleanup: Teacher demo; chain kept away from necks. https://demos.swarthmore.edu/physics/2015/07/chain-fountain/