Competency #4
Answer and Explanation
Analyze Situations involving Archimedes' or Bernoulli's Principle
Since you were asked to define the buoyant force in your own words, answers will vary. Hewitt, et al. define the buoyant force as:
The net upward force that a fluid exerts on an immersed object.
Key things to check for in your definition:
Did you specify that the buoyant force is an upward force? The buoyant force always acts in the direction opposite that of gravity.
Did you specify that the object must be partially or fully submerged in a fluid? If the object is not in a fluid (that is, a gas or liquid), then there is no buoyant force acting on the object.
Did you say that the buoyant force only acts on floating objects? If so, you were overly specific. Note that buoyant forces act on each of the following three objects:
- a piece of wood floating on the top of a lake
- a rock sitting on the bottom of the lake
- a boat that has capsized and is halfway down to the bottom of a lake