2018-02-20
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GRAVITATION
Gravitation is a very important force in the universe. Every object has a gravitational pull which is like magnetism. But, unlike magnetism, gravitation is not only in iron and steel. It is in every object large or small; but large objects, such as earth, have a stronger pull than small ones.
Isaac Newton, the great scientist of the seventeenth century, first studied gravitation. When he was a boy, he often saw how apples fell to the ground. He wondered why they fell towards the earth and why they did not fly up into the sky.According to the law which he later produced everything In the universe attracts everything else towards itself. The sun attracts the earth and the earth attracts the sun.
The earth attracts the moon and the moon attracts the sun. Although the bigger object has the stronger attraction, all objects, in fact, have some attraction too but we do not notice the gravitational pull of a book because the pull of the earth is very much greater.
Why does the earth always move round the sun, and not fly off into cold space?
The sun's gravitation gives the answer. The earth always tries to move away in a straight line, but the sun always pulls it back. So it continues on its journey round and round the sun.
The sun is one of the stars in the galaxy, in which there are about 100,000 million stars. It is not in the middle of the galaxy, but rather near one edge.
There are millions of galaxies in the universe and so there are thousands of minions of millions of suns. Many astronomers believe that some of these suns have planets as our sun does. Gravitation is the force which holds all the atoms of a star together. It holds the sun together and it holds the atoms of the earth together, It holds us on the earth. Einstein produced a new law of gravitation. Its main results are the same as the results of Newton's law; but in very small and fine matters Einstein's law gives different results. One of these is that gravitation bends light a little; but according to Newton's law gravitation has very little effect on light. Einstein showed this fact by means of mathematics and not by experiment. And astronomers later proved by experiments that Einstein was right.
Planet Earth — our Common Home
Ecology is a science which is concerned with the interrelations of organisms and their environment, which is with everything that surrounds them.
The ecologists are faced by a lot of problems in the modem world — the air we breathe, the water we drink, the food we eat, the soil we stand on, the great projects we construct...
There are about 6 billion people in the world at present. The population is growing very fast and scientists believe that in a few decades it will be too big for the earth to support.
The Earth is being constantly damaged in different ways. Speaking about the growth of population we have to admit the increase of industries and their harmful effects on the environment — the pollution of air from choking factory chimneys and the pollution of water because of industrial wastes.
Among the other serious problems which our planet is facing are: the increasing consumption of energy and water, the pollution of air by car exhausts, the increasing hole in the atmospheric ozone layer, the rivers that are poisoned by industrial and agricultural chemicals, the forests that are felled and vast forest territories that are devastated by fire and acid rains.
Besides, armed conflicts and local wars add to the critical situation on the planet.
The Earth is just a huge spaceship and mankind is its crew. Can quarrels and killings among the crew be permitted? What will then hap pen to the spaceship? What will happen to mankind?
If we realize the coming danger, we’ll see that we should find solutions to all the problems to survive.
What should be done to change the situation for the better?
• We must change people’s attitude towards the environment.
• We should stop the pollution of air and water.
• We must save more energy and water and try to use other sources of energy (solar and tidal energy, the energy of the wind, subterranean hot waters, etc.).
• We must protect the ozone layer from harmful industrial products.
• We should prevent animals from extinction.
These and many other steps should be taken already now to make our planet a safer and better place to live in. We, human beings, must act.
A MACHINE SHOULD WORK, AND A MAN SHOULD THINK
The robots of our time resemble humans very little. According to specialists, the main thing for them is not to look like people, but to do their work for them. Factories which are equipped with automatic machine-tools, transfer lines and management information systems place a lot of hope in them.
Automation sought out areas where a robot can operate as well as a person but where people don’t like working. In other words the man has created the robot so as not to become a robot himself.
The first generation of robots appeared in the 60s and they were complex and capricious in maintenance. They could perform operations of the type «take off- put on» or «pick up-bring».
They could pick up items only from definite positions determined by a rigid programme.
Today, to avoid errors, robots are supplied with vision (TV camera) and hearing (microphone). They can perform more complex production and operations – painting, soldering, welding and assembly work. A more complex task lies ahead – to remove people completely from production areas where there are harmful fumes, excessively high or low temperatures and pressure. People should not work in conditions that are dangerous. Let the robots replace them there – and the sooner, the better.
Generally speaking a single robot by itself is hardly of any use in production. It must be coupled in design with other equipment, with a system of machines, machine-tools and other devices. We must set up robotized complexes and flexible productions capable of transferring easily and quickly to an output of new goods.
Flexible production systems consist, as a rule of several machine-tools with numerical programmed control or of processing centres-machine-tools equipped with microprocessors. An all-purpose computer controls the entire cycle, including the storage facilities. One hundred per cent automated production is no longer a dream.
There is already talk of making thinking robots. Apparently, robots will appear which will be able to discourse, understand and acquire the ability to study. May be they will be able to enrich our concepts about the world around us. But one thing is certain – a robot will never be able to grasp even the semblance of such emotions as love, honour, pride, pity, courage and selflessness.
