What it shows
An object does not need to float in order to experience the buoyant force.
In this example we see a cup of water at rest on a pan balance. When the demonstrator pushes a finger down into the liquid, the buoyant force of the liquid pushes up on the finger with a force equal to the weight of the displaced water. The incompressible liquid pushes down on the balance as it pushes up on the finger.
Setting it up
A clear plastic cup of water works well. Food coloring is optional. A camera may be necessary in a large lecture hall. Dip the finger smoothly and slowly.
