Buoyancy: Summary

The answers to the ConcepTests are given below and will open in a separate window. 
Key points from this module:
  • The buoyant force is the resultant fluid force acting on the body when a stationary body is partially or totally submerged in a fluid.
  • This resultant force is due to the higher hydrostatic pressure force acting from below the object.
  • Archimedes principle tells us that the force is equal to the weight of the fluid displaced and acts upward.
  • This analysis assumes that the fluid has a constant specific weight (incompressible).
From studying this module, you should now be able to:
  • Draw a free body diagram of an object and of a partially-submerged object.
  • Apply Archimedes principle to hydrostatic situations.
  • Determine the buoyant force.
  • Calculate the amount of fluid displaced by an object.
  • Find the height of a partially submerged object.

Prepared by Janet deGrazia, Department of Chemical and Biological Engineering, University of Colorado Boulder