Buoyancy
... on the other hand does not displace much water so the rock sinks because the amount of water it displaces weighs less than the rock. If an object displaces an amount of water that equals its own weight, then the object will neither sink nor float. So when considering whether an object floats or sinks, you have to take into account its weight, density and its volume. In water there are three states of buoyancy: positive buoyancy, which causes an object to float; negative buoyancy, causes an object to sink; and neutral buoyancy, causes an object to neither sink nor float. For scuba divers this makes all the difference in the world in how much they enjoy the sport. For most people, their body has a natural tendency to float or to be positively buoyant. This would be a tiring process for a diver if they constantly had to fight against his or her positive buoyancy to stay at depth. For this reason, it is necessary for divers to wear weights. If a diver were to wear only weights, this would cause another problem, now the diver begins to sink or to become negatively buoyant. The diver would now have to struggle to stay afloat. To counter act this negative buoyancy a diver must also wear a device which is know as a BC jacket (Buoyancy Compensator jacket). This jacket is used to counteract the negative buoyancy by filling it with air. This air changes the body’s displacement and causes the diver to become positively buoyant. The density of the fluid also an important factor that affects buoyancy. For example, seawater is denser than freshwater. This means that a heavier object can float much easier in saltwater than in freshwater because the saltwater that the object displaces weighs more. A diver’s ideal situation while...