TOPIC:

ID Code: F2-21
Purpose: Demonstrates the reaction force using a liquid.
Description: A beaker of water is balanced by two brass weights. Stick your finger into the water about up to the first knuckle, the water side will go down. The water exerts a buoyant force on your finger, so your finger exerts a reaction to the buoyant force on the water, thereby causing the water side to go down.
Availability: Available

See the Physics Question of the Week for 1/13/2014 for an example of how this demonstration can be used in class interaction and discussion: lecdem.physics.umd.edu/question-of-the-week-archive.html