Why does ice float on water?
We may have often put ice cubes into a glass of cold drink, but have we ever wondered. Ice floats on water because it is lighter than that. Long ago, a Greek scientist named Archimedes also wondered about it. He hit upon a solution, which is today, known as the Archimedes principle. He put forward the law of flotation of bodies. According to this law, whenever a body is placed in water, two forces act upon it—the weight of the body acting downwards and the buoyant force of water acting upwards. If the upward thrust of water, the body floats. In simple words, a lighter object always floats on water. On the other hand, if the weight of a body is more than the weight of the water displaced by it, it sinks. This phenomenon is same as a piece of word floating on the surface of water. Since the weight of wood is nearly half the weight of an equal volume of water, half of the wood remains submerged, while the other half can be seen on the top. Generally, when a liquid changes into a solid, its molecules come closer to each other and it contracts. As a result, the volume of the liquid decreases and its density increases. Hence a substance becomes heavier in solid state than in the liquid state.
Ice floats because it is slightly lighter than water
Water is a peculiar liquid. When it freezes and changes into ice, its molecules—instead of coming closer-expand. Thus, the volume of ice increases. As a result of this expansion, its density decreases to nine-tenths of the density of water. So if you try freezing nine liters of water, you will get ten liters of ice!
The ice cubes floating in your drink are very much similar to the icebergs floating in the sea. This also explains the reason why the maximum portion of the giant icebergs remains submerged in water while only a tip (1/10 part) is above water.
In the olden days, a number of ships sank, including the Titanic (sank of April 15, 1912), as they could not see the icebergs submerged in water. This is why icebergs are considered to be dangerous. The ice under water (9/10 of the whole) displaces water. The weight of the water displace equals the weight of the ice. The largest iceberg in 1956 was in the South Pacific. It was 335 kilometers long and 97 kilometers wide.