The three basic forces that act on an immiscible particle suspended in a liquid are:Weight: the gravitational force acting on the particle. It acts downward.Buoyancy: the lifting or upward force that a carrying liquid imparts on a floating or submerged body. It is equal to the weight of the displaced volume of the carrying liquid.Drag: the resistance to motion that the carrying fluid imparts on a particle. It is opposite to the direction of motion of the particle relative to the liquid, and is basically due to frictional effects and the shape of the particle.For a sphere rising at constant velocity, the buoyant force is dominant and acts upward. The gravity force (weight) acts downward and the drag force acts opposite to the direction of motion. Thus for a rising sphere, Buoyancy = Weight + Drag