This module uses screencasts and an interactive simulation to derive the equation for buoyancy and demonstrate how it is used. Screencasts are used to show how specific weight, volume of a fluid, and volume of an object are related. An interactive simulation and example problems allow the user to test themselves. We suggest using the learning resources in the following order:

  1. Attempt to answer the multiple-choice ConcepTest and solve the example problem before watching the screencasts or working with the simulations.
  2. Watch the two screencasts that describe how the equation for buoyancy is derived and answer the question in the second screencast.
  3. Use the interactive simulation to further understand the behavior of buoyancy.
  4. Try to solve the two example problems before watching the solutions in the screencasts.
  5. Answer the ConcepTests.

Buoyancy is one of the fundamental concepts of fluids, and is used in a number of applications such as how submarines dive and ascend, how hot air balloons fly, and why certain objects float or sink.

          This module is intended for fluid mechanics courses.

Before studying this module, you should:

  • Be able to do a force balance.
  • Know how to use specific weights of both fluids and solids.

After studying this module, you should be able to:
  1. Draw a free body diagram of an object and of a partially-submerged object.
  2. Apply Archimedes principle to hydrostatic situations.
  3. Determine the buoyant force.
  4. Calculate the amount of fluid displaced by an object.
  5. Find the height of a partially-submerged object.