Final answer:
Buoyant force is the net upward force on any object in any fluid. It is equal to the weight of the fluid displaced by the object. Examples of buoyant force include a boat floating on water and a balloon filled with helium.
Step-by-step explanation:
Buoyant force is the net upward force on any object in any fluid. When an object is submerged in a fluid, it displaces a certain amount of fluid. According to Archimedes' principle, the buoyant force on an object is equal to the weight of the fluid it displaces.
For example, when a boat floats on water, the buoyant force on the boat is equal to the weight of the water it displaces. Another example is a balloon filled with helium. The buoyant force on the balloon is greater than its weight, causing it to float in the air.