Final answer:
The fraction of an iron anchor's weight supported by buoyant force in saltwater is determined by Archimedes' principle, which states that this force equals the weight of the displaced fluid. The anchor's volume and the densities of the anchor and saltwater are needed to calculate the specific fraction.
Step-by-step explanation:
The fraction of an iron anchor's weight that will be supported by the buoyant force when submerged in saltwater can be determined by the principle of buoyancy, also known as Archimedes' principle. This principle states that the buoyant force on an object submerged in a fluid is equal to the weight of the fluid that is displaced by the object. Since saltwater is denser than fresh water, it will exert a greater buoyant force on the submerged object.
To calculate the specific fraction, you would divide the buoyant force by the weight of the iron anchor. The result would tell you what fraction of the anchor's weight is supported by the water. For a complete answer, the volume of the anchor and the exact densities of the anchor and saltwater would be needed.