Somewhere I happen to read that when some floating material is dropped in bucket full of water such that the water does not spill out, the weight of the total system increases. Well, but i dont understand why this should happen. the body floats as the buoyant force of water balances its weight. due to which the weight appears to be zero and the body floats. why should the weight of the whole system change in spite of addition of a zero? how to foretell the change in weight that is going to happen in such a case?