Explain how a normal body which sinks in water could be made to float?

Answer 1

To begin with, if we are speaking of a human body, most human bodies (especially in the US) are well fed enough, that they have sufficient fat stores such that they will foat in water. Thus, to consider a "normal body" which "sinks in water" it means that this particular body is (overall) more dense than the water. For this to happen, we must be talking about a human body which has very little fat (perhaps a long distance runner, a sikly malnurished person, or a body builder - all three body styles having a greater percentage than normal of muscle, bone and/or connective tissue versus the percentage of fat). Such a person could simply breath in deeply, thereby expanding the lungs and creating a larger volume of the body, but adding essentially no weight (i.e. making one's body "less dense"), and, in turn, allowing for the body to float - or more scientifically speaking, become bouyant. This is all simple physics and related to overall density of the material of the body; a weight versus volume relationship. If a body displaces more mass than a similar volume of water would, then it will sink when placed in water. If the body displaces less weight than a similar sized volume of water weighs, than it floats if placed into the water.