In middle school (static or uniform motion), the direction of buoyancy is always vertical and will not change. The reason of buoyancy: the pressure difference between the upper and lower surfaces of an object immersed in liquid or gas is expressed by the formula: F floating =F up -F down = ρ liquid gV discharged. Here, F downward and F upward refer to the pressures on the upper and lower surfaces of an object immersed in liquid or gas, and here, the buoyancy of the object can be considered as the resultant force of the pressures on the upper and lower surfaces of the object.

In addition, the reason why buoyancy is always vertical upward can also be seen from the perspective of pressure. At the same depth in liquid or gas, the pressures in all directions are equal, and the buoyancy direction is vertical upward because the lower surface of the object in solution is deeper than the upper surface, so the lower surface pressure is greater than the upper surface pressure.