Almost everyone of us would have seen ships and boats sailing in water but how many of you ever thought about the science behind it. Isn't that strange to know that heavy steel ships don't sink in water whereas a small metallic pen sinks down? So, why do ships not sink in water, read on to find out.

No doubt the floating boats have signs of some Supernatural creator in them. He holds the heavy navigational traffic in water. But what is the mechanism behind it?

Mechanism Behind Floating Ships

Two main factors in ship design keep the ship floating:

1. Weight of ship (loaded and unloaded).

2. Shape of ship.

The ship designers calculate the weight of loaded ships and compare it to the weight of the water that will be displaced when the ship is placed in the water. The more water that is displaced, the higher the ship will float (i.e. in theory, if you keep loading a ship, its weight will exceed the weight of displaced water and it will sink).


The tendency of a body to uplift an immersed body, because of the upward thrust of the liquid, is known as Buoyancy. The force tending to uplift the body is called the Force of Buoyancy or buoyant force and is equal to the weight of the liquid displaced. When a body is immersed wholly or partially in a liquid, it is lifted up by a force equal to the weight of liquid displaced by the body. This statement is known as Archimedes Principle.

According to Archimedes Principle:

An object floats when it has displaced its weight in the medium, in which it is floating. A large ship is hollow and big and easily displaces its weight in the ocean or fresh water. That's why it floats easily and not sinks in water.


1. If the force of buoyancy is more than the weight of the liquid displaced, then the body will float.

2. If the force of buoyancy is less than the liquid displaced, then the body will sink down.

More simply, if the volume of water displaced is more than the volume of object, the object will float.

Now you know why ships don't sink. That was interesting to learn about Buoyancy, that's the law create by God, this is indeed very amazing.

Tag: why does a ship not sink in water

Solar energy nuclear power and wind mills are the three common renewable energy sources that are easily available. Their details, limitations and issues are also mentioned below:

Solar Energy

The most popular and simple way of alternate energy is solar energy i.e. the electricity produced by sun's radiation. There are two methods of achieving the above-mentioned goal:

1. Photovoltaic Cells

A photovoltaic cell converts sunlight directly into electricity. These cells normally produces 1-2 Watts of electricity which is not sufficient enough to operate appliances, therefore a number of such cells are bound together to form large modules and even these modules can be connected to form arrays to produce required power output. PV systems can easily be used at any remote site like RF stations. They are also used to power watches, calculators, road signs and streetlights. Electricity produced by these modules produces Direct Current (DC) whereas the normal home appliances that we use are Alternate Current (AC) appliances therefore an inverter is required to convert the DC into AC.

2. Solar Power Plants

They indirectly generate electricity when the heat from solar thermal collectors is used to heat a fluid that produces steam to move the turbine that is connected to ordinary generators.


The output of solar energy systems depend on amount of solar radiation produced by the sun at that particular site and at that particular time of the year. Moreover, the PV modules are only 18% efficient however; efforts are being made to increase their efficiency to a remarkable level. 

Wind Mills

The windmill systems includes wind turbine with a conventional generator. The wind flowing produces mechanical energy in a turbine that is converted into electricity from a conventional generator coupled to the turbine. These systems works essentially the same as generation from fossil fuels except that instead mechanical energy produced by using steam it is produced from the combustion of fossil fuels, the mechanical movement is produced by the wind flow. Modern wind turbines range from 600 kW to 5 MW of power output, although turbines with rated output of 1.5–3 MW have become very common for commercial use.


The power output of a turbine is a function of the cube of the wind speed, so as wind speed increases, power output increases. Areas where winds are stronger and more constant, such as offshore and high altitude sites are preferred locations for wind farms. Since wind speed is not constant, the energy production also varies.

Nuclear Power Plants

Nuclear power plants normally use nuclear fission reaction to produce energy. In fission the nucleus of large, atoms such as uranium 235 or plutonium 239, is split into two or more smaller nuclei producing large amount of kinetic energy along with free neutrons and gamma radiation. The free neutrons are used to produce more such fission reactions. A cooling system removes heat from reactor core and transports it to the area where thermal energy is used to heat fluid producing steam to rotate the turbine coupled with conventional generators.


It is fact that the nuclear waste is hazardous to the environment but these risks can be eliminated by using improved method to handle the waste products. Moreover, nuclear reactors produce virtually no air pollution and the energy produce is much higher than the fossil-fuel generators. In addition, nuclear power produces far less waste material than fossil-fuel based power plants. Coal burning plants are particularly noted for producing large amounts of toxic and mildly radioactive ash due to concentrating naturally occurring metals and radioactive material from the coal.


The nuclear power plants have high initial investment and the maintenance cost is also very high.


The renewable energy systems use fuel that has unlimited reserves, free of cost and generalized existence like sun-rays for solar systems and air for wind mill systems, even uranium for nuclear power plants are very abundant in nature. It is approximately as common as tin or germanium in Earth's crust, and is about 35 times more common than silver. In addition, more importantly they are none or far less pollutant than the conventional sources.

However, these renewable energy systems produce no air or water pollution but do have some indirect impacts on the environment. For example, manufacturing the photovoltaic cells used to convert sunlight into electricity consumes silicon and produces some waste products. In addition, large solar thermal farms and windmill can also harm desert ecosystems if not properly managed.

Man in the name of technology and scientific advancement does these damages to the Mother Earth like the weapons that we make to safe lives are actually killing ourselves by one way or the other. It is we who in the blind quest of technological advancement had willing or unwillingly destroyed the entire ecological system and it is our prime duty now to save it as our survival depends on its existence.

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Tag: Solar Energy vs Wind Mills vs Nuclear Power 

A suspension bridge is the type of a bridge, which is mainly concerned with the application of tension than compression. These bridges are usually suspended by the main cables (chain or rope) that are anchored with the towers at both ends of the bridge. Earlier, towers were not provided in suspension bridges because they were usually constructed for short spans. But nowadays, among all the longest bridges of the world 14 bridges are suspension bridges. There are the many types of suspension bridges that exist today, described below:

Simple Suspension Bridge

It is the oldest type of suspension bridge, usually constructed as a foot bridge. In this type of bridge, a flexible deck is provided which is supported by the cables anchored to the earth.

Under Spanned Suspension Bridge

In this type of suspension bridge the main cables are provided below the deck. The cables are anchored to the ground similarly as the above type. Few numbers of suspension bridges have been constructed like this due to the instability of the deck.

Stressed Ribbon Bridge

It is the modified form of the simple suspension bridge in which deck lies on the main cables but it is stiff not flexible.

Suspended-Deck Suspension Bridge

In this type of suspension bridge, the stiffed deck is attached to the main cables with the help of suspenders. This type is suitable for heavy traffic and light rail.

Above are the most common types of suspension bridges. Some types of suspension bridge are hybrid types. These types of suspension bridges have some portion of deck similar to under-spanned suspension bridge.

How Structural Failure Occurs

Structural failure concerns with reduction in the load bearing capability of a structural component or element, or the main structure. Structural failure is commenced when the material is stressed to its upper strength limit, thus causing rupture or extreme deformations. The ultimate strength of the material or the system is the limit of the load bearing capacity. On reaching this limit, the construction materials could already been damaged, and their load carrying capacity is suddenly decreased permanently. If the system is properly designed, a local collapse should normally not be a cause of instant or gradual failure of the complete building. The ultimate failure strength of the construction elements should be carefully considered in the design of structures to prevent failure.

Design Parameters

A progressive collapse of a building or structure is initiated from local fracture that later spreads to include the main section of the facility. Current concerns with such collapses stem basically from modifications in building practices and improper structural designs. Strategies for mitigating the structural failures can be evaluated using a thoughtful risk assessment, supported by modern computational tools. It is important to arrange soil testing on the actual site before the detailed planning starts. Buildings, like all construction, are designed to sustain specific loads without excessive deformation to prevent failure. The live loads consist of the weights of humans, objects, rain, snow, and the wind pressure, while the dead load is that of the building itself. With buildings consisting of a few floors, strength usually involves adequate rigidity, and the vital design is essentially that of the roof that will endure the weather effects. However, the roof design is of a minor significance for tall buildings, and the major considerations are that of the building supports.

Prevention Of Structural Damage

Structures may fail due to numerous reasons that need to be thoroughly deliberated during the initiation, design, planning, executing, and the monitoring processes of the project. Faulty construction has been the most important cause of structural failures. This includes the use of salty sand to produce concrete, use of inferior steel, improver riveting, incorrect nut tightening torques, defective welding, and other wrong engineering practices. Designers of structures should also consider the seismic effects to prevent damage due to the earthquakes. Earthquakes may cause problems concerning the foundations when the damp land liquefies.

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