Final answer:
The cube will experience a greater buoyant force in a saturated salt solution than in water due to the greater density of the salt solution. When the cube's dimensions are reduced from 5 cm to 4 cm, the buoyant force it experiences in water decreases, as less water is displaced due to the smaller cube size.
Step-by-step explanation:
The question involves understanding how buoyant force works and how it changes based on different fluids and the dimensions of an object. According to Archimedes' principle, the buoyant force is equal to the weight of the fluid displaced by the object. When a cube with a side of 5 cm is immersed in water versus a saturated salt solution, the cube will experience a greater buoyant force in the salt solution because the density of the salt solution is greater than that of water, leading to the displacement of a heavier weight of fluid.
When the side of the cube is reduced from 5 cm to 4 cm and then immersed in water, the buoyant force experienced by the cube will decrease.
This is because the volume of the displaced water, which determines the buoyant force, is smaller due to the smaller dimensions of the cube. The new volume of the cube, with a side of 4 cm, is less than that with a side of 5 cm, hence less water is displaced and the buoyant force is reduced.