Density used in real-life situations

A real life situation that uses density are ships and submarines. However, it can be hard to calculate whether an object would float on water. An object must contain a lot of air to float, therefore if the ship's density is less than the density of the water, the ship will be successful in floating. This is because ships store air in tanks which have a small density and have little mass. On the other hand, submarines are able to move around under water because their tanks of air are empty and have a higher density than water. Its overall density is greater than the surrounding water, and the submarine begins to sink. A submarine or a ship can float because the weight of water that it displaces is equal to the­ weight of the ship. This displacement of water creates an upward force called the buoyant force and acts opposite to gravity, which would pull the ship down.