an 8.3kg object with a volume of .86x10^-3 m^3 is submerged in water. What is the buoyant force on the object?

Answer 1

The mass of the object is irrelevant. The buoyant force is determined entirely by the object's volume. The buoyant force is equal to the weight of the water that the object displaces (that is, equal to the weight of water that would fill up .86 x 10-3 m^3). Figure out how much that volume of water weighs, and that's the buoyant force.

Answer 2

The mass of the object is a red herring; the bouyant force depends on the volume only, The NET force will be the difference between the bouyant force and the weight. The volume involved is 0.86 liters, so the bouyant force is 0.86 kilograms.