The wood floats on the surface because the density of the wood is less than the density of the water. The trees dug "hollow" has become a canoe, their own gravity becomes smaller, can carry more people, canoe row of water volume becomes larger, increased the available buoyancy. Toothpaste rolled into a group, sink in the water, And "hollow" toothpaste skin can float on the water, that "hollow" can adjust the relationship between buoyancy and gravity. The use of "hollow" to increase the volume, thereby increasing the buoyancy, so that objects can float on the surface.Floating Bridge
As the hull is made hollow, the volume of the water is increased and the buoyancy is increased, and the buoyancy is equal to its own gravity, so it can float on the water. It is the use of objects floating in the liquid condition F floating = G to work, as long as the ship's gravity unchanged, regardless of the ship in the sea or the river, it is the same buoyancy. (Only the sea water density is different, the ship's water line is different) According to Archimedes principle, F float = ρ liquid gV row, it is in the sea and the river immersed in the water volume is different.The size of the ship is usually used to express its displacement The Floating Bridge
The pontoon bridge is often used in military, also known as war bridge, because of its simple and fast characteristics. Military pontoon erection, as a temporary means of transport, is generally used to pass the army, baggage. Sometimes used to block the action of the other party, the pontoon on the troops stationed, the use of pontoon and the other water operations. At this time, the pontoon became a water trenches. A bridge, a bridge that floats on a surface with a boat or pontoon.
The army used the standard pilots of military equipment, then called the bridge. The history of the pontoon is based on China.Floating Bridge
There are two types of pontoon structure: the traditional form is in the boat or floating box on the beam, and then bridge the deck. The form of the boat, or the vessel is connected to the end of the boat, into a string, or the boat is closely arranged into a belt. In order to maintain the location of the pontoon axis is not offset, in the upstream and downstream cable anchor required. For the cross-strait connected, in the cross-strait need to set the transition beam or springboard. In order to meet the fluctuation of water level, the two sides should also set up or down the bridge or lift the bridge. The pontoon can be used for people, roads, railways. Its structure is not complicated, the demolition is also convenient, but the high cost of maintenance. Usually available for emergency relief or as a temporary transport facilities, wartime can be used to ensure that the military quickly through the river military standard boat bridge, in order to increase its mobility, commonly used light metal made of self.Floating Bridge