If we tied the a piece of iron on wood , but the wood shape is such that the weight of combined system (iron +wood) is less than the water displaced by wood , then only the combined system will float on water. Otherwise the (wood+iron) will sink.
Arccoding to Archimedes principle ,when a body is wholly or partially immersed in a fluid ,it experience an upward thrust equal to the weight of the fluid displaced. If the weight of fluid displaced is greater than the weight of substance than the substance will float on liquid.
As shown in figure if the (wood+ iron) displaced more weight of water then itself then it can float on water surface.
Rate this question :
What is buoyancy?AP - Physics & Chemistry
Iron sinks in watAP - Physics & Chemistry