A lead cube, 2 cm on each side is lowered by a string until it is submerged in water in a can. The density of lead is 11.3 kg/m^3
How much force is exerted on the string?

The force in the string is equal to the weight of the lead cube pulling downward minus the buoyant force of the water pushing upward. Archimedes principle says the buoyant force is equal to the weight of the water the lead cube displaces. Can you complete this now?