PHS 100 - Self Assessment

Competency #4

The correct answer is A.

Which of the following best describes the buoyant force?

The net upward force that a fluid exerts on a fully or partially immersed object.

This is the best description of the buoyant force. A fluid exerts pressure on all sides of an object, perpendicular to its surface. Since pressure increases with depth, the pressure on the object is greater on and near the bottom than it is on or near the top. A buoyant force is present on both fully and partially immersed objects (that is, objects that sink and float).
The upward force that a fluid exerts on the bottom of a partially immersed object.

The buoyant force is the net force exerted by the fluid. That means that the forces exerted on all sides of the object must be added together (while being sure to take the direction into account) to find the net force on the object.
The net upward force that is present in water and other liquids (but not in air or other gases).

The buoyant force exists in all fluids. “Fluids” is a term that is used to include liquids and gases
The force that causes the pressure to decrease as the velocity of the fluid increases.

This answer is a misstatement of Bernoulli's principle.
The force that is equal to the density for an object that floats

The buoyant force is equal to the force of gravity for a floating object with no other forces acting on it. However, the buoyant force is NOT equal to the density.