Physics 212, Extra Credit for Week #2: due Dec 16, 1997, at 7 PM

Measuring the buoyant force.

This project may be done by teams of 1-3 individuals. You must design an experiment that allows you to measure directly the buoyant force on an object immersed in some fluid. For example, you might place an object into a bucket of fluid; if the object floats, then you might add mass to the object until it just starts to sink. The total mass of the object plus the extra mass on top of it can be used to calculate the downward force of gravity. When the object just begins to sink, the downward force of gravity must be slightly larger than the upward force of buoyancy.

You must measure the buoyant force of at least three objects made of different materials: at least one must be more dense than the fluid, and at least one must be less dense than the fluid.

Describe carefully the fluid you use, the container which holds it, and every object you place in the fluid. Measure the objects' size and mass, and do the same for any extra weights and other apparatus in your experiment. Draw two pictures of your device, showing how it measures the buoyant force on an object less dense than the fluid, and on an object more dense than the fluid.

Compare the buoyant force on each object with the theoretical value. If they are not the same, explain the discrepancy.

Submit a report which contains the pictures and descriptions of your experiment, as well as the results. You may also include interesting items you discovered during the course of the procedure.