28 novembre 2011
Elephants
Elephants are the largest land-animals alive today. With a height of 10-12 feet, they weigh between 3 and 6 (7000 to 13000 lbs) tons.
Elephants are found in Africa and India. Their natural habitat can be anywhere as long as the place is warm and they have access to food and water.
Elephants are herbivorous animals. They feed on vegetation i-e grasses, herbs and bark etc. they consume near 150 kg of food per day. This is actually 5% of their body weight! They can’t digest 40% of the eaten food and make up for an inefficient digestive system by eating a lot. 3 to 5 gallons of water per day is also needed by them to survive. They spend most of their time eating. 16 hours of the day are spent feeding themselves. That is why they can get only about three hours of sleep a day.
Female elephants live in herds. The herd is headed by the eldest member. The females look after themselves and their cubs. It is also common that they try to care for injured or weak herd members, which is very unusual in animals. The young ones are looked after until they are old enough to live by themselves.
In sharp contrast, male elephants live alone. Their solitary lives are spent eating and fighting other males for breeding. The older ones usually dominate the younger ones and get to mate. Thus, most of the breeding is done by the older elephants.
The most prominent features of elephants are their tusks and large ears. The tusks are very valuable. Most of the elephant-hunting is after them.
Elephants are considered as quite intelligent animals. Their intelligence is comparable to dolphins. Their brain weighs 5 kg (11 lbs).
Elephants have very powerful senses of smell and hearing. Sound receptors are not only present in the ears but also in their feet and trunk. The feet also have some sensors which can detect sound frequencies through land. They have poor eyesight.
The elephants have also been domesticated. They have been vastly used in warfare for centuries. Their huge size and strength is unmatchable by any other source. A charging elephant was once the most dreadful sight a soldier could face. However, in spite of all their uses, they were very difficult to tame and raise.
Despite their portrayal as gentle animals, they can be very dangerous if they choose to attack. Between 2001 and 2005, near 300 deaths were reported in Assam, India as a result of elephant attacks. Their immense size means that they can crush any other living beings even the enormous Rhinos.
The number of elephants in the world today is about 700,000. Only a tenth of the population is in India, the rest are in Africa. A large number is also domesticated in zoos and circuses etc.
25 novembre 2011
Man Power to Nuclear Power
For a very long time in our history, we relied upon manpower and animal power as the sole source of energy to do work in our daily lives. This was hard work, and often, very slow. It was not efficient, either. Many spent their whole lives laboring.
However, in the 18th century, things changed. The steam engine was invented. It relied on coal as fuel to produce an enormous quantity of energy. At first, it was quite crude, needing huge amount of fuel, but just a century later, it was perfected and was driving mills, factories, rails and huge steamships across oceans. It drove the Industrial Revolution and made us more technologically advanced than we could dream of earlier.
In the course of the 19th and 20th century, emphasis shifted from steam power to electrical power. It was more efficient and could do more than just provide power. It could drive appliances and much more. It could be created where energy was available and transferred to where it was needed.
But electrical energy was not powerful enough to drive ships, rails or later cars and planes. That is where the Internal Combustion Engine came in. Relying on petrol or diesel, it was efficient than steam powered engines and could produce power strong enough to run large vehicles.
Electrical Engines needed electricity. Electricity was created in power plants. Fuel in coal, natural gas or oil was fed into the thermal plants, where it converted water to steam and steam was used to drive turbines and thus providing mechanical energy which was converted to electrical energy in a Generator. Now it could be transferred to where it was needed pretty economically.
Fossil fuels, coal, gas and oil were expensive. There were cheaper ways of generating electricity. One such way is Hydroelectric Power Plants. Driven by a running river, the turbines revolve and generators change this energy to electricity. But hydro plants needed dams. Dams were huge concrete structures used to stop and gather water until it has enough force to drive turbines. This is a renewable energy source because no fuel is needed.
There are other ways to generate power, too. Wind and Solar power has been used at a small scale but they are not as effective as other methods.
In 1945, world entered the nuclear age. Nuclear power was not only destructive, but it had an immense potential to provide power. Soon after, nuclear reactors were constructed, providing cheap electricity. The process of the chain reaction which releases huge destructive energy, if not controlled, but when slowed down in reactors, can provide a smaller amount of energy for a long period of time. This energy is used to drive turbines and make electricity.
Nuclear power has hazards, too. They are prone to accidents which can be very deadly. Fukishima in Japan and Chernobyl in Ukraine were disasters on a very large scale and exhibit the dangers of nuclear power. Radioactive waste is a headache, too. Disposing it is hazardous, although it is done far away from civilizations.
Nuclear power has a huge potential which has not been utilized up to now. It may provide energy for hundreds, if not thousands of years to come.
first post
Hello, this is my first post!
