Complex sentence: In science, buoyancy is an upward force exerted by a fluid that opposes the or an object submerged in the fluid, experiences greater pressure at the bottom of the column than at the top.
Split into simpler sentences: In science, buoyancy is an upward force exerted by a fluid that opposes the weight of an immersed object. Thus a column of fluid, or an object submerged in the fluid, experiences greater pressure at the bottom of the column than at the top.