Physics Demo Number: 011

Approximate

Run Time: 5 min

Visualization of Buoyant Force as Proportional to Displaced Volume of Water

Demo Description

A red plastic bowl is used as a boat in which to float differing loads of Aluminum plates.

The amount of displaced water is clearly seen for each configuration of added loading, as evidenced by the second and third photos.

Scientific Principles

• Buoyant force is equal to the weight of the water displaced by the submerged part of the boat hull.

• The total weight of the boat and contents must be balanced by the buoyant force.

Equipment

• Red plastic bowl cut to fit inside of  water cylinder for fiber optic total internal reflection demonstration.

• Three dedicated Aluminum load plates.

Equipment Location

• The water vessel resides on [C-1-5] in Kit (053).

• The load plates and red plastic bowl live in Kit(011) as part of Kit (053) on [C-1-5].

Instructions

The first photo shows the three load weights, the flotation chamber, and the boat.

The second photo shows the red boat floating nearly on top of the water, under no load conditions.

The third photo shows the red boat floating with nearly 90% of its hull submerged to support the three load weights that are now inside the boat.

Note that the lensing effect of the water in the flotation chamber makes the water-displacing part of the hull very visible even from the back of the big lecture halls.