# Physical World

## Class 11 NCERT Physics

### NCERT

1   Some of the most profound statements on the nature of science have come from Albert Einstein, one of the greatest scientists of all time. What do you think did Einstein mean when he said: “The most incomprehensible thing about the world is that it is comprehensible”?

##### Solution :

The Physical world around us is full of different complex natural phenomena so the world is in-comprehensible. But with the help of study and observations it has been found that all these phenomena are based on some basic physical laws and so it is comprehensible.

2   “Every great physical theory starts as a heresy and ends as a dogma". Give some examples from the history of science of the validity of this incisive remark.

##### Solution :

The statement above is true. Validity of this incisive remark can be validated from the example of moment of inertia. It states that the moment of inertia of a body depends on its energy. But according to Einstein's mass-energy relation , energy depends on the speed of the body.

3   "Politics is the art of the possible”. Similarly, "Science is the art of the soluble”. Explain this beautiful aphorism on the nature and practice of science.

##### Solution :

It is well known that to win over votes, politicians would make anything and everything possible even when they are least sure of the same. and in Science the various natural phenomena can be explained in terms of some basic laws. So as 'Politics is the art of possible' similarly 'Science is the art of the soluble'.

4   Though India now has a large base in science and technology, which is fast expanding, it is still a long way from realizing its potential of becoming a world leader in science. Name some important factors, which in your view have hindered the advancement of science in India.

##### Solution :

Some important factors in our view which have hindered the advancement of science in India are:$\\$ $\bullet$ Proper funds are not arranged for the development of research work and laboratories.$\\$ The labs and scientific instruments are very old and outdated.$\\$ $\bullet$ Most of the people in India are uneducated and highly traditional. They don't understand the importance of Science.$\\$ $\bullet$ There is no proper employment opportunity for the science educated person in India.$\\$ $\bullet$ There are no proper facilities for science education in schools and colleges in India.

5   No physicist has ever “seen” an electron. Yet, all physicists believe in the existence of electrons. An intelligent but superstitious man advances this analogy to argue that ‘ghosts’ exist even though no one has ‘seen’ one. How will you refute his argument?

##### Solution :

No physicist has ever seen an atom but there are practical evidences which prove the presence of electron. Their size is so small, even powerful microscopes find it difficult to measure their sizes. But still its effects could be tested$\\$ On the other end there is no phenomena which can be explained on the basis of existence of ghosts.$\\$ Our senses of sight and hearing are very limited to observe the existence of both. So there is no comparison between the two given cases.

6   The shells of crabs found around a particular coastal location in Japan seem mostly to resemble the legendary face of a Samurai. Given below are two explanations of this observed fact. Which of these strikes you as a scientific explanation?$\\$

##### Solution :

Explanation (b) is correct is a scientific explanation of the observed fact

7   The industrial revolution in England and Western Europe more than two centuries ago was triggered by some key scientific and technological advances. What were these advances ?

##### Solution :

More than two centuries ago, England and Western Europe invented steam engine, electricity, theory of gravitation and the explosives. Steam engines helped them in the field of hat and thermodynamics, theory of gravitation in field of motion and making guns and cannons. These progresses brought about industrial revolution in England and Western Europe.

8   It is often said that the world is witnessing now a second industrial revolution, which will transform the society as radically as did the first. List some key contemporary areas of science and technology, which are responsible for this revolution.

##### Solution :

Some of the key contemporary areas of science and technology which may transform the society radically are:$\\$ $\bullet$ Development of super-fast computers$\\$ $\bullet$ Internet and tremendous advancement in information technology$\\$ $\bullet$ Development in Biotechnology$\\$ $\bullet$ Development of super-conducting materials at room temperature$\\$ $\bullet$ Development of robots.

9   Write in about $1000$ words a fiction piece based on your speculation on the science and technology of the twenty-second century.

##### Solution :

Imagine you alongwith your friends are in a spaceship which is moving towards Mars. The body of the spaceship is made of a specially designed matter which becomes more harder as its temperature increases. The spaceship is using nuclear fuel and there are three nuclear power plants in a spaceship. Two of them work alternatively and the third is for emergency. The speed of the spaceship is very high and all of you are very happy. The energy produced in power plants is converted into electric energy which runs the motors of the spaceship. You alongwith your friends reach safely on Mars, collects data, takes photographs and then returns to the Earth. On the return journey, the spaceship collides with an object in the space due to which two power plants stop to work. Now, only one power plant is working and due to overheating its efficiency is decreasing continuously. You and your friends try to reduce the temperature of the power plant by flowing air in the plant and try to repair the fuse of the other power plants. Finally, fuse of one other plant is repaired and start to work before the first plant crosses the danger limit of an excess of temperature. Finally, you and your friends return safely to Earth

10   Attempt to formulate your ‘moral’ views on the practice of science. Imagine yourself stumbling upon a discovery, which has great academic interest but is certain to have nothing but dangerous consequences for the human society. How, if at all, will you resolve your dilemma?

##### Solution :

In our view a type of discovery which is of great academic interest but harmful for human society should not be made public because Science is for the society, society is not for science.