Perelman's most interesting topics in physics. Extracurricular activity "this entertaining physics"

The proposed edition of “Entertaining Physics” by Ya. I. Perelman repeats the four previous ones. The author worked on the book for many years, improving the text and supplementing it, and in last time During the author's lifetime, the book was published in 1936 (thirteenth edition). When releasing subsequent editions, the editors did not set as their goal a radical revision of the text or significant additions: the author selected the main content of “Entertaining Physics” in such a way that, while illustrating and deepening the basic information from physics, it is not outdated to this day. In addition, so much time has passed since 1936 that the desire to reflect the latest achievements in physics would have led to a significant increase in the book and to a change in its “face”. For example, the author’s text about the principles space flights is not outdated, and there is already so much factual material in this area that one can only refer the reader to other books specifically devoted to this topic.

The fourteenth and fifteenth editions (1947 and 1949) were published under the editorship of prof. A. B. Mlodzeevsky. Associate Professor took part in the preparation of the sixteenth edition (1959–1960). V. A. Ugarov. When editing all publications published without an author, outdated figures were only replaced, projects that did not justify themselves were removed, and individual additions and notes were made.

FROM THE AUTHOR'S PREFACE TO THE THIRTEENTH EDITION

In this book, the author strives not so much to impart new knowledge to the reader, but to help him “find out what he knows,” that is, to deepen and revive the basic information from physics that he already has, teach him how to consciously manage it and encourage him to use it in many ways. . This is achieved by examining a motley series of puzzles, intricate questions, entertaining stories, amusing problems, paradoxes and unexpected comparisons from the field of physics, related to everyday phenomena or drawn from well-known works of science fiction fiction. The compiler used the latter kind of material especially widely, considering it the most relevant to the purposes of the collection: excerpts from novels and stories by Jules Verne, Wells, Mark Twain and others are given. The fantastic experiences described in them, in addition to their temptingness, can also play an important role in the quality of teaching when teaching. live illustrations.

The compiler tried, as far as he could, to give the presentation an outwardly interesting form and to convey the attractiveness of the subject. He was guided by the psychological axiom that interest in a subject increases attention, facilitates understanding and, consequently, contributes to more conscious and lasting assimilation.

Contrary to the custom established for this kind of collections, in “Entertaining Physics” very little space is devoted to the description of funny and spectacular physical experiments. This book has a different purpose than collections that offer material for experimentation. The main goal of “Entertaining Physics” is to excite the activity of the scientific imagination, to accustom the reader to think in the spirit of physical science and to create in his memory numerous associations of physical knowledge with the most diverse phenomena of life, with everything with which he usually comes into contact. The attitude that the compiler tried to adhere to when revising the book was given by V.I. Lenin in the following words: “A popular writer leads the reader to a deep thought, to a deep teaching, based on the simplest and generally known data, pointing out with the help of simple reasoning or well-chosen main examples conclusions from these data, leading the thinking reader to further and further questions. A popular writer does not assume a reader who does not think, does not want, or cannot think; on the contrary, he assumes in the undeveloped reader a serious intention to work with his head and helps him to do this serious and difficult work, guides him, helps him take his first steps and teaching move on on your own" [V. I. Lenin. Collection cit., ed. 4, vol. 5, p. 285.].

In view of the interest shown by readers in the history of this book, we provide some bibliographic information about it.

“Entertaining Physics” was “born” a quarter of a century ago and was the first-born in the large book family of its author, which now numbers several dozen members.

"Entertaining Physics" was lucky enough to penetrate - as letters from readers testify - into the most remote corners of the Union.

The significant distribution of the book, testifying to the keen interest of wide circles in physical knowledge, imposes on the author serious responsibility for the quality of its material. The awareness of this responsibility explains the numerous changes and additions to the text of “Entertaining Physics” during repeated editions. The book, one might say, was written during all 25 years of its existence. In the latest edition, barely half of the text of the first has been preserved, and almost none of the illustrations.

The author received requests from other readers to refrain from revising the text, so as not to force them “to purchase each re-edition because of a dozen new pages.” Such considerations can hardly relieve the author from the obligation to improve his work in every possible way. “Entertaining Physics” is not a work of fiction, but a scientific work, albeit a popular one. Its subject - physics - even in its initial foundations is constantly enriched with fresh material, and the book must periodically include it in its text.

On the other hand, one often hears reproaches that “Entertaining Physics” does not devote space to such topics as the latest advances in radio technology, the fission of the atomic nucleus, modern physical theories, etc. Reproaches of this kind are the fruit of a misunderstanding. “Entertaining Physics” has a very specific goal; consideration of these issues is the task of other works.

Current page: 1 (book has 13 pages total) [available reading passage: 4 pages]

Yakov Perelman
Entertaining physics. Book 1

Publishing house "RIMIS" is a laureate of the Literary Prize named after. Alexandra Belyaev 2008.

The text and drawings are restored from the book by Ya. I. Perelman “Entertaining Physics”, published by P. P. Soykin (St. Petersburg) in 1913.

* * *

Outstanding popularizer of science

The singer of mathematics, the bard of physics, the poet of astronomy, the herald of astronautics - this was and remains in the memory of Yakov Isidorovich Perelman, whose books were sold all over the world in millions of copies.

The name of this remarkable person is associated with the emergence and development of a special – entertaining – genre of scientific popularization of the fundamentals of knowledge. The author of more than a hundred books and brochures, he had the rare gift of talking about dry scientific truths in an exciting and interesting way, arousing burning curiosity and inquisitiveness - these are the first stages of the independent work of the mind.

It is enough to even briefly familiarize yourself with his popular science books and essays to see the special direction of their author’s creative thinking. Perelman's goal was to show ordinary phenomena in an unusual, paradoxical perspective, while at the same time maintaining the scientific impeccability of their interpretation. The main feature of his creative method was his exceptional ability to surprise the reader and capture his attention from the very first word. “We early cease to be surprised,” Perelman wrote in his article “What is Entertaining Science,” “we early lose the ability that prompts us to be interested in things that do not directly affect our existence... Water would be, without a doubt, the most amazing substance in nature, and the Moon - the most amazing sight in the sky, if both did not come into view too often.”

To show the ordinary in an unusual light, Perelman brilliantly used the method of unexpected comparison. Sharp scientific thinking, a huge general and physical and mathematical culture, the skillful use of numerous literary, scientific and everyday facts and plots, their amazingly witty, completely unexpected interpretation led to the appearance of fascinating scientific and artistic short stories and essays that are read with unflagging attention and interest. However, entertaining presentation is by no means an end in itself. On the contrary, it is not to turn science into fun and entertainment, but to put the liveliness and artistry of presentation at the service of understanding scientific truths - this is the essence of Yakov Isidorovich’s literary and popularization method. “So that there is no superficiality, so that the facts are known...” - Perelman strictly followed this thought throughout his 43-year creative career. It is in the combination of strict scientific reliability and an entertaining, non-trivial form of presentation of material that the secret of the continued success of Perelman’s books lies.

Perelman was not an armchair writer, divorced from living reality. He responded promptly to the practical needs of his country in a journalistic manner. When in 1918 the Council of People's Commissars of the RSFSR issued a decree on the introduction of the metric system of weights and measures, Yakov Isidorovich was the first to publish several popular brochures on this topic. He often gave lectures in work, school and military audiences (he gave about two thousand lectures). At the suggestion of Perelman, supported by N.K. Krupskaya, in 1919 the first Soviet popular science magazine “In the Workshop of Nature” began to be published (under his own editorship). Yakov Isidorovich did not remain aloof from the secondary school reform.

It must be emphasized that Perelman’s teaching activities were also marked by genuine talent. For a number of years he taught courses in mathematics and physics at higher and secondary educational institutions. In addition, he wrote 18 textbooks and teaching aids for the Soviet Unified Labor School. Two of them - “Physical Reader”, issue 2, and “New Problem Book on Geometry” (1923) received the very high honor of taking places on the shelf of Vladimir Ilyich Lenin’s Kremlin Library.

The image of Perelman is preserved in my memory - a widely educated, extremely modest, somewhat shy, extremely correct and charming person, always ready to help the help you need to your colleagues. He was a true worker of science.

On October 15, 1935, the House of Entertaining Science began to function in Leningrad - a visible, embodied exhibition of Perelman’s books. Hundreds of thousands of visitors walked through the halls of this unique cultural and educational institution. Among them was Leningrad schoolboy Georgy Grechko, now a pilot-cosmonaut of the USSR, twice Hero Soviet Union, Doctor of Physical and Mathematical Sciences. The fate of two other cosmonauts - Heroes of the Soviet Union K. P. Feoktistov and B. B. Egorov - is also connected with Perelman: in childhood they became acquainted with the book “Interplanetary Travel” and became interested in it.

When did the Great Patriotic War, Ya. I. Perelman’s patriotism and his high consciousness of civic duty to the Motherland were clearly manifested. Remaining in besieged Leningrad, he, no longer a young man (he was 60 years old), steadfastly endured, along with all the Leningraders, the inhuman torments and difficulties of the blockade. Despite enemy artillery shelling and aerial bombardment of the city, Yakov Isidorovich found the strength to overcome hunger and cold and walk from end to end of Leningrad to attend lectures in military units. He lectured army and naval reconnaissance officers, as well as partisans, on what was extremely important at that time - the ability to navigate the terrain and determine distances to targets without any instruments. Yes, and entertaining science served the purpose of defeating the enemy!

To our great chagrin, on March 16, 1942, Yakov Isidorovich passed away - he died during the siege from hunger...

The books of Ya. I. Perelman continue to serve the people to this day - they are constantly republished in our country, they enjoy constant success among readers. Perelman's books are widely known abroad. They have been translated into Hungarian, Bulgarian, English, French, German and many other foreign languages.

At my suggestion, one of the craters on the far side of the Moon was given the name “Perelman”.

Academician V. P. Glushko

Excerpts from the preface to the book “Doctor of Entertaining Sciences” (G. I. Mishkevich, M.: “Znanie”, 1986).

Preface

The proposed book, in terms of the nature of the material collected in it, is somewhat different from other collections of this type. Physical experiments, in the strict sense of the word, are given a secondary place in it; entertaining tasks, intricate questions and paradoxes from the field of elementary physics, which can serve the purposes of mental entertainment, are brought to the fore. By the way, some works of fiction (Jules Verne, C. Flammarion, E. Poe, etc.) are used as similar material; issues of physics are touched upon. The collection also includes articles on some interesting issues of elementary physics, usually not discussed in textbooks.

Of the experiments, the book includes mainly those that are not only instructive, but also entertaining, and, moreover, can be performed using objects that are always at hand. Experiments and illustrations for them were borrowed from Tom Titus, Tisandier, Beuys and others.

I consider it a pleasant duty to express my gratitude to the learned forester I.I. Polferov, who provided me with irreplaceable services in reading the latest proofs.

St. Petersburg, 1912

Ya. Perelman

Stevin's drawing on the title page of his book ("Miracle and Not a Miracle").

Chapter I
Addition and decomposition of movements and forces

When do we move faster around the Sun - during the day or at night?

Weird question! The speed of the Earth's movement around the Sun cannot, it would seem, be connected in any way with the change of day and night. In addition, on Earth it is always day in one half and night in the other, so the question itself is apparently meaningless.

However, it is not. It's not about when Earth moves faster, but about when We, people, we are moving rather in global space. And this changes things. Don't forget that we make two movements: we rush around the Sun and at the same time we rotate around the earth's axis. Both of these movements fold up– and the result is different, depending on whether we are on the day or night half of the Earth. Take a look at the drawing - and you will immediately see that at night the rotation speed is added to the forward speed of the Earth, and during the day, on the contrary, is taken away from her.

Rice. 1. People on the night half of the globe move around the Sun faster than on the day half.

This means that at night we move faster in world space than during the day.

Since each point of the equator runs about half a mile per second, for the equatorial strip the difference between midday and midnight speed reaches a whole mile 1
Versta is a Russian unit of distance measurement equal to five hundred fathoms or 1,066.781 meters. – Note ed.

Per second. For St. Petersburg (located at the 60th parallel) this difference is exactly half as much.

The Cartwheel Mystery

Attach a white wafer to the side of the rim of a cart wheel (or to a bicycle tire) and observe it as the cart (or bicycle) moves. You will notice a strange phenomenon: while the wafer is at the bottom of the rolling wheel, it is visible quite clearly; on the contrary, in the upper part of the wheel the same wafer flashes so quickly that you do not have time to see it. What is it? Really top part Does the wheel move faster than the lower one?

Your bewilderment will further increase if you compare the upper and lower spokes of a rolling wheel: it turns out that while the upper spokes merge into one continuous whole, the lower ones remain visible quite clearly. Again, it is as if the top of the wheel is rolling faster than the bottom. But meanwhile, we are firmly convinced that the wheel moves evenly in all its parts.

What is the answer to this strange phenomenon? Yes, simply that the upper parts of every rolling wheel really move faster than the ones below. This seems completely incredible at first glance, and yet it is so.

Simple reasoning will convince us of this. Let us remember that each point of a rolling wheel makes two movements at once: it revolves around an axis and at the same time moves forward along with this axis. Happening addition of two movements- and the result of this addition is not at all the same for the upper and lower parts of the wheel. Namely, at the top of the wheel there is a rotational movement is added to translational, since both movements are directed in the same direction. In the lower part of the wheel, the rotational movement is directed in the opposite direction and is taken away from progressive. The first result, of course, is greater than the second - and that is why the upper parts of the wheel move faster than the lower ones.

The top of a rolling wheel moves faster than the bottom. Compare the movements of AA" and BB".

That this is indeed the case can be easily verified by a simple experiment, which we recommend doing at the first favorable opportunity. Stick a stick into the ground next to the wheel of a standing cart so that the stick is against the axis (see Fig. 2). On the wheel rim, at the very top and at the very bottom, make a mark with chalk; these marks are dots A And B in the picture - they will have to fight against the stick. Now roll the cart forward a little (see Fig. 3) until the axle is about 1 foot away from the stick. 2
Foot - (English) foot– foot) is a British, American and Old Russian unit of distance measurement equal to 30.48 centimeters. Not included in the SI system. – Note ed.

, – and notice how your marks have moved. It turns out that the top mark is A– has moved significantly more than the lower one – B, which only slightly moved away from the stick at an upward angle.

In a word, both reasoning and experience confirm the idea, strange at first glance, that the upper part of any rolling wheel moves faster than the lower.

Which part of the bicycle moves slowest than all the others?

You already know that not all points of a moving cart or bicycle move equally quickly, and that those points of the wheels that move the slowest are those that this moment come into contact with the ground.

Of course, all this only takes place for rolling wheels, and not for one that rotates on a fixed axis. In a flywheel, for example, both the top and bottom points of the rim move at the same speed.

The mystery of the railway wheel

An even more unexpected phenomenon occurs in a railway wheel. You know, of course, that these wheels have a protruding edge on the rim. And so, the lowest point of such a rim when the train moves does not move forward at all, but backward! This is easy to verify with reasoning similar to the previous one - and we leave it to the reader to reach the unexpected, but quite correct conclusion that in a fast moving train there are points that move not forward, but backward. True, this reverse movement lasts only an insignificant fraction of a second, but this does not change the matter: reverse movement (and quite fast at that - twice as fast as a pedestrian) still exists, contrary to our usual ideas.

Rice. 4. When the railway wheel rolls along the rail to the right, the point R his rim moves back to the left.

Where is the boat coming from?

Imagine that a steamboat is sailing on a lake, and let the arrow a in Fig. 5 depicts the speed and direction of its movement. A boat is sailing across him, and the arrow b depicts its speed and direction. If you are asked where this boat departed from, you will immediately indicate the point A on the shore. But if you ask the passengers of a sailing ship with the same question, they will indicate a completely different point.

This happens because the passengers of the ship see the boat moving not at all at right angles to its movement. It should not be forgotten that they do not feel their own movement. It seems to them that they themselves are standing still, and the boat is rushing at their speed. reverse direction(remember what we see when we travel in a carriage railway). That's why for them the boat does not move only in the direction of the arrow b, but also in the direction of the arrow c, – which is equal a, but directed in the opposite direction (see Fig. 6). Both of these movements - real and apparent - add up, and as a result, it seems to the passengers of the ship that the boat is moving diagonally along a parallelogram built on b And c. This diagonal, indicated in Fig. 6 with a dotted line expresses the magnitude and direction of apparent movement.

Rice. 5. Boat ( b) is sailing across the steamer ( a).

This is why passengers will claim that the boat set sail at B, not in A.

When we, rushing along with the Earth in its orbit, meet the rays of some star, then we judge the place of origin of these rays as incorrectly as the above-mentioned passengers make a mistake in determining the place of departure of the second boat. Therefore, all the stars appear to us to be slightly moved forward along the path of the Earth's movement. But since the speed of the Earth’s movement is negligible compared to the speed of light (10,000 times less), this movement is extremely insignificant and can be detected only with the help of the most precise astronomical instruments. This phenomenon is called “light aberration”.

Rice. 6. Passengers of the ship ( a) seems like a boat ( b) floats from a point B.

But let's return to the problem about the steamship and the boat discussed above.

If you are interested in such phenomena, try, without changing the conditions of the previous problem, to answer the questions: in what direction is the ship moving? for boat passengers? To what point on the shore is the ship heading, according to its passengers? To answer these questions you need to be on line a construct, as before, a parallelogram of velocities. Its diagonal will show that for the passengers of the boat the steamer seems to be sailing in an oblique direction, as if about to moor at some point on the shore lying (in Fig. 6) to the right B.

Is it possible to lift a person on seven fingers?

Anyone who has never tried this experiment will probably say that lifting an adult on your fingers is impossible. Meanwhile, this is done very easily and simply. Five people should participate in the experiment: two put their index fingers (of both hands) under the feet of the person being lifted; the other two support his elbows with the index fingers of his right hand; finally, the fifth one places his index finger under the chin of the person being lifted. Then, on command: “One, two, three!” – all five of them unanimously lift their comrade, without noticeable tension.

Rice. 7. You can lift an adult with seven fingers.

If you are doing this experiment for the first time, you will be amazed at the unexpected ease with which it is performed. The secret of this ease lies in the law decomposition strength The average adult weight is 170 pounds 3
Pound is a unit of mass; 1 pound = 0.454 kg. – Note ed.

; these 170 pounds put pressure on seven fingers at once, so each finger only bears about 25 pounds. It is relatively easy for an adult to lift such a load with one finger.

Raise a carafe of water with a straw

This experience also seems completely impossible at first glance. But we have just seen how careless it is to trust “first glance.”

Take a long, solid, strong straw, bend it and insert it into a carafe of water as shown in Fig. 8: its end should rest against the wall of the decanter. Now you can lift it - the straw will hold the decanter.

Rice. 8. A decanter of water hangs on a straw.

When introducing a straw, you must ensure that the part of it that rests against the wall of the decanter is completely straight; otherwise the straw will bend and the whole system will collapse. The whole point here is that the force (the weight of the decanter) acts strictly in length Straws: In the longitudinal direction, straw has great strength, although it breaks easily in the transverse direction.

It is best to first learn how to perform this experiment with a bottle and only then try to repeat it with a decanter. We recommend that inexperienced experimenters place something soft on the floor, just in case. Physics is a great science, but there is no need to break decanters...

The following experiment is very similar to the one described and is based on the same principle.

Pierce a coin with a needle

Steel is harder than copper, and therefore, under a certain pressure, a steel needle should pierce a copper coin. The only trouble is that when a hammer hits the needle, it will bend and break it. It is necessary, therefore, to arrange the experiment in such a way as to prevent the needle from bending. This is achieved very simply: stick the needle into the cork along its axis - and you can get down to business. Place a coin (kopeck) on two wooden blocks, as shown in Fig. 9, and place a plug with a needle on it. A few careful blows and the coin is broken. The cork for the experiment must be dense and high enough.

Rice. 9. The needle pierces the copper coin.

Why are pointed objects prickly?

Have you ever thought about the question: why does a needle penetrate different objects so easily? Why is it easy to pierce cloth or cardboard with a thin needle and so difficult to pierce with a thick rod? Indeed, in both cases, it would seem that the same force acts.

The fact of the matter is that the strength is not the same. In the first case, all the pressure is concentrated on the tip of the needle, while in the second case the same force is distributed over a much larger area of the end of the rod. The area of the needle tip is thousands of times less than the area of the end of the rod, and therefore, the pressure of the needle will be thousands of times greater than the pressure of the rod - with the same force of our muscles.

In general, when we talk about pressure, it is always necessary, in addition to force, to also take into account the size of the area on which this force acts. When we are told that someone receives 600 rubles. salary, then we do not yet know whether it is a lot or a little: we need to know - per year or per month? In the same way, the effect of a force depends on whether the force is distributed per square inch 4
Inch - (from Dutch. duim– thumb) is the Russian name for a unit of measurement of distance in some European non-metric systems, usually equal to 1/12 or 1/10 (“decimal inch”) of a foot of the corresponding country. Word inch introduced into the Russian language by Peter I at the very beginning of the 18th century. Today, an inch is most often understood as an English inch equal to 2.54 cm smooth. – Note ed.

Or concentrates on 1/100 sq. millimeter.

For exactly the same reason, a sharp knife cuts better than a dull one.

So, sharpened objects are prickly, and sharpened knives cut well because enormous power is concentrated on their points and blades.

Chapter II
Gravity. Lever arm. Scales

Up the slope

We are so accustomed to seeing weighty bodies rolling down an inclined plane that the example of a body freely rolling upward along it seems at first glance almost a miracle. However, there is nothing easier than to arrange such an imaginary miracle. Take a strip of flexible cardboard, bend it into a circle and glue the ends together - you will get a cardboard ring. Glue a heavy coin, such as a fifty-kopeck piece, to the inside of this ring with wax. Now place this ring at the base of the inclined board so that the coin is in front of the fulcrum, at the top. Release the ring and it will roll up the slope on its own (see Fig. 10).

Rice. 10. The ring rolls up on its own.

The reason is clear: the coin, due to its weight, tends to occupy the lowest position in the ring, but, moving with the ring, it thereby forces it to roll upward.

If you want to turn the experience into a focal point and wow your guests, you need to stage it a little differently. Attach a heavy object to the inside side of an empty round hat box; then, having closed the box and placed it properly in the middle of the inclined board, ask the guests: where will the box roll if it is not held - up or down? Of course, everyone will unanimously say that it’s down, and they will be quite amazed when the box rolls up before their eyes. The tilt of the board should, of course, not be too great for this.

Proposed edition of “Entertaining Physics” by Ya.I. Perelman repeats the four previous ones. The author worked on the book for many years, improving the text and supplementing it, and for the last time during the author’s lifetime the book was published in 1936 (thirteenth edition). When releasing subsequent editions, the editors did not set as their goal a radical revision of the text or significant additions: the author selected the main content of “Entertaining Physics” in such a way that, while illustrating and deepening the basic information from physics, it is not outdated to this day. In addition, the time after 1936 so much has already passed that the desire to reflect the latest achievements of physics would have led to a significant increase in the book and to a change in its “face”. For example, the author’s text on the principles of space flight is not outdated, and there is already so much factual material in this area that one can only refer the reader to other books specifically devoted to this topic.

The fourteenth and fifteenth editions (1947 and 1949) were published under the editorship of prof. A. B. Mlodzeevsky. Associate Professor took part in the preparation of the sixteenth edition (1959 - 1960). V.A. Ugarov. When editing all publications published without an author, outdated figures were only replaced, projects that did not justify themselves were removed, and individual additions and notes were made.

Contrary to the custom established for this kind of collections, in “Entertaining Physics” very little space is devoted to the description of funny and spectacular physical experiments. This book has a different purpose than collections that offer material for experimentation. The main goal of “Entertaining Physics” is to excite the activity of the scientific imagination, to accustom the reader to think in the spirit of physical science and to create in his memory numerous associations of physical knowledge with the most diverse phenomena of life, with everything with which he usually comes into contact. The attitude that the compiler tried to adhere to when revising the book was given by V.I. Lenin in the following words: “A popular writer leads the reader to a deep thought, to a deep teaching, based on the simplest and generally known data, pointing out with the help of simple reasoning or well-chosen main examples conclusions from these data, leading the thinking reader to further and further questions. A popular writer does not assume a reader who does not think, does not want, or cannot think; on the contrary, he assumes in the undeveloped reader a serious intention to work with his head and helps him to do this serious and difficult work, guides him, helps him take his first steps and teaching move on on your own” [V. I. Lenin. Collection cit., ed. 4, vol. 5, p. 285.].

In view of the interest shown by readers in the history of this book, we provide some bibliographic information about it.

“Entertaining Physics” was “born” a quarter of a century ago and was the first-born in the large book family of its author, which now numbers several dozen members.

“Entertaining physics” was lucky enough to penetrate - as letters from readers testify - into the most remote corners of the Union.

“Entertaining Physics,” in addition to her second book, contains several other works by the same author. One is intended for a relatively unprepared reader who has not yet begun the systematic study of physics, and is entitled “Physics at Every Step” (published by “Detizdat”). The other two, on the contrary, refer to those who have already completed their high school physics course. These are “Entertaining mechanics” and “Do you know physics?”. The last book is like the completion of “Entertaining Physics”.

1936 Ya. Perelman

Chapter first. SPEED. ADDITION OF MOVEMENTS.

How fast are we moving?

A good runner runs a sports distance of 1.5 km in about 3 minutes. 50 sec. (world record 1958 - 3 minutes 36.8 seconds). To compare with the usual pedestrian speed - 1.5 m per second - you need to do a small calculation; then it turns out that the athlete runs 7 m per second. However, these speeds are not entirely comparable: a pedestrian can walk for a long time, for hours, doing 5 km per hour, while an athlete is only able to maintain a significant running speed a short time. An infantry military unit moves at a run three times slower than the record holder; she does 2 meters per second, or more than 7 kilometers per hour, but has the advantage over the athlete that she can make much greater transitions.

It is interesting to compare the normal gait of a person with the speed of such proverbial slow animals as a snail or a turtle. The snail fully lives up to the reputation attributed to it by the saying: it moves 1.5 mm per second, or 5.4 m per hour - exactly a thousand times less than a person! Another classically slow animal, the turtle, is not much faster than the snail: its usual speed is 70 m per hour.

Agile next to a snail and a turtle, a person will appear before us in a different light if we compare his movement with other, even not very fast, movements in the surrounding nature. True, it easily overtakes the flow of water in most lowland rivers and does not lag far behind the moderate wind. But a person can successfully compete with a fly flying 5 m per second only on skis. A person cannot drive a hare or a hunting dog even on a horse. A person can compete in speed with an eagle only on an airplane.

Yakov Perelman, one of the most famous representatives of the genre of popular science literature, was born on December 4, 1882 in the provincial town of Bialystok, Grodno province, into the family of an accountant and a teacher. At the end primary school in 1895 he entered the Bialystok real school. While still a student at the school, in 1899 he published his first article “On the expected rain of fire” in the local newspaper “Grodno Provincial Gazette”. In August 1901, Perelman entered the Forestry Institute in St. Petersburg. Already in his first year, he began collaborating with the magazine “Nature and People”, making his debut in it with the essay “A Century of Asteroids”.

Yakov Perelman became famous in 1913, after the publishing house of Peter Soykin published his first book, “Entertaining Physics.” The book not only had incredible success among a wide range of readers, but was also well received in the academic community, receiving more than favorable reviews from scientists.

In 1916, the second part of Perelman’s “Entertaining Physics” was published. During his life, he published a large number of popular science books devoted to various branches of science and technology, many of which were reprinted several times and continue to be republished to this day. Visual and figurative, and most importantly, fascinating manner of presentation made his books popular among millions of readers.

In 1916, while working at the Petrograd Special Meeting on Fuel, Perelman made a proposal to move clocks forward an hour in order to save fuel, thus becoming the first in the country to propose introducing the so-called maternity leave time.

From 1918 to 1923, Perelman was an inspector of the department of the Unified Labor School of the People's Commissariat of Education of the RSFSR, taught at various educational institutions and compiled learning programs in physics, mathematics and astronomy. He was a member of the editorial boards of the journals "Science and Technology", "Pedagogical Thought", worked in the science department of the Leningrad "Red Newspaper", and later, in the early thirties, was a member of the presidium of the Leningrad group for the study of jet propulsion, where he headed the propaganda department and was involved in the development of the first Soviet anti-hail missile.

In October 1935, the company he created opened in Leningrad. unique museum- The House of Entertaining Science, which introduced schoolchildren to the achievements of science and technology in a visual and educational way. Unfortunately, almost all of the museum’s exhibits were lost during the war, and currently only descriptions of some of them have been preserved. During the siege of Leningrad by Nazi troops, despite hunger and difficult living conditions, Yakov Perelman continued to work on articles and books, and gave lectures on terrain orientation without instruments to soldiers of the Leningrad and Red Banner Baltic Fleet. Unfortunately, he did not have the chance to survive the blockade - on March 16, 1942, Yakov Isidorovich Perelman died from general exhaustion caused by hunger.

Books (22)

5 minutes to think

The book contains sections: “Problems about heaven and earth”, “Riddles of living nature”, “Deceiving feelings”, “5 minutes to think”, “Can you reason”, “Entertaining problems”, “Interesting numbers”, “Puzzles” ", "Funs and tricks", "Games, fun and tricks with matches", "Dominoes", "Chess", "Crosswords".

Quick count

The simplest and most easily learned techniques for quick mental counting. They are designed for average abilities and do not have in mind public performances on the stage, but the needs of everyday life.

Those who use the book should remember that successful mastery of its instructions presupposes not mechanical, but quite conscious use of techniques and, in addition, more or less lengthy training.

Perpetual motion machines. Why are they impossible?

A “perpetual motion machine” is an imaginary machine that, without borrowing energy from outside, would operate non-stop and do some work.

A machine that would continuously maintain only its own motion, without producing any additional work, would not be a “perpetual motion machine” in the strict sense of these words.

Distant Worlds

“In the vast sea of bright points that dot the starry sky, there are luminaries that are millions of times closer to us and have a completely different nature than all the other stars. At a quick glance, they are lost among thousands of others; Only sometimes the brightness of some of them and the calm, almost flickering light attracts our attention. And if, having noticed such stars, we begin to monitor them day after day, remembering their position among neighboring ones, then we will soon discover a significant feature in them...”

Live geometry textbook

Here is a book by the famous popularizer of science Yakov Isidorovich Perelman “Living Textbook of Geometry”, which is very different from the well-known “Entertaining Geometry” - mainly in its purpose: this book is more of an educational nature. However, do not rush to put the book away.

This is by no means a dry presentation of educational material. The presentation of the "Living Textbook of Geometry" is special, facilitating the assimilation of the subject. Here the inquisitive reader will find a lot of useful, interesting and accessible material, illustrated with drawings.

Entertaining arithmetic

There are a number of original and translated collections in Russian that generally pursue the same goal as this book: to revive school mathematics by introducing interesting problems, entertaining exercises, interesting theoretical and practical information...

“Entertaining Arithmetic” is, for the most part, an attempt to propose a number of new, not yet developed plots of arithmetic entertainment...

Entertaining geometry

“Entertaining Geometry” was written both for friends of mathematics and for those readers from whom for some reason many attractive aspects of mathematics were hidden...

To arouse the reader’s interest in geometry or, in the author’s words, “to instill a desire and cultivate a taste for its study is the direct task of this book”...

Entertaining geometry in the open air and at home

The book was written not so much for the friends of mathematics as for its enemies.

She does not mean mainly those who already have an inclination for mathematics, and also not those who have not yet begun to study it at all. The author intends the book primarily for that broad category of readers who became acquainted with this science at school (or are now still getting acquainted) with no particular interest or animation, having at best only cold respect for it. To make geometry attractive to them, to instill a desire for it and to cultivate a taste for its study is the direct task of this book.

Entertaining mechanics

“Entertaining Mechanics” is a unique textbook on physics and mechanics by the outstanding popularizer of science Ya.I. Perelman, which will help develop a child’s intelligence, make it easier to learn the material covered in class and significantly expand the school curriculum. The young reader will be offered interesting examples of the application of the basic laws of mechanics in technology, sports and even circus tricks, as well as fascinating physical quizzes.

Entertaining physics

The main goal of Entertaining Physics is to excite the scientific imagination... this is achieved by examining a motley array of puzzles, tricky questions, entertaining stories, amusing problems, paradoxes and unexpected comparisons from the field of physics.

Entertaining physics. Book 2

In the proposed book, as in the first, the compiler strives not so much to impart new knowledge as to revive and refresh the simplest information on physics that the reader already has.

The purpose of the book is to stimulate the activity of the scientific imagination, to teach one to think in the spirit of physics and to develop the habit of versatile application of one’s knowledge.

Entertaining tasks and experiences

This collection includes materials from various books by the outstanding popularizer of science Ya.I. Perelman, the author or compiler of which he was.

The young reader will find here many interesting experiments and problems from the fields of physics, mathematics, geometry and other scientific entertainment.

Squaring a circle

Of the geometric problems posed by ancient mathematicians, three stand out, remarkable in that they became extremely widely known even among non-mathematicians. These tasks are briefly formulated as follows:

“Doubling the cube”: construct an edge of a cube whose volume is twice the volume of the given cube.