Ya. I. Perelman

Entertaining physics

EDITORIAL

The proposed edition of "Entertaining Physics" Ya.I. Perelman repeats the previous four. The author has been working on the book for many years, improving the text and supplementing it, and in last time during the life of the author, 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 chose the main content of "Entertaining Physics" in such a way that, illustrating and deepening the basic information from physics, it has not become outdated so far. In addition, the time after 1936. so much has passed that the desire to reflect latest achievements physics would lead both 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 For example, the author's text on the principles of space flight is not outdated, but actual material there is already so much in this area that one can only refer the reader to other books specifically devoted to this topic.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 edited by prof. A. B. Mlodzeevsky. The preparation of the sixteenth edition (1959 - 1960) was attended by Assoc. V.A.Ugarov. When editing all publications that came out without an author, only obsolete figures were replaced, projects that did not justify themselves were withdrawn, and separate additions and notes were made.

In this book, the author seeks not so much to inform the reader of new knowledge, but rather to help him “learn what he knows”, i.e., to deepen and revive the basic information from physics that he already has, to teach him to consciously dispose of them and to encourage their versatile application. . This is achieved by considering a motley series of puzzles, intricate questions, entertaining stories, amusing problems, paradoxes and unexpected comparisons from the field of physics related to the circle everyday phenomena or drawn from well-known works of science fiction fiction. material last kind the compiler used it especially widely, considering it to be the most appropriate for the purposes of the collection: excerpts from the novels and stories of Jules Verne, Wells, Mark Twain, and others are given. The fantastic experiences described in them, in addition to their temptation, can also play a lot when teaching important role as living illustrations.

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

Contrary to the custom established for such collections, in "Entertaining Physics" very little space is given to the description of amusing and spectacular physical experiments. This book has a different purpose than collections that offer material for experimentation. the main objective"Entertaining physics" - 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 installation, which the compiler tried to adhere to when revising the book, was given by V. I. Lenin in the following words: “ Popular Writer leads the reader to deep thought, to deep teaching, proceeding from the most simple and well-known data, indicating with the help of simple reasoning or well-chosen examples the main conclusions from these data, prompting the thinking reader to further and further questions. The popular writer does not presuppose an unthinking, unwilling or unable to think reader; on the contrary, he presupposes in the undeveloped reader a serious intention to work with his head and helps him to do this serious and difficult work, guides him, helping him to take his first steps and teaching to go on independently” [V. I. Lenin. Sobr. cit., ed. 4, vol. 5, p. 285.].

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

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

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

Significant distribution of the book, indicating a keen interest broad circles to physical knowledge, imposes on the author a serious responsibility for the quality of her material. The consciousness of this responsibility explains the numerous changes and additions in the text of "Entertaining Physics" in the reprints. 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 reworking the text so as not to force them "because of a dozen new pages to purchase each reprint." Such considerations can hardly relieve the author of the obligation to improve his work in every possible way. "Entertaining physics" is not piece of art, and the essay is scientific, albeit popular. 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 latest advances radio engineering, the splitting of the atomic nucleus, modern physical theories, etc. Reproaches of this kind are the fruit of a misunderstanding. "Entertaining Physics" has a well-defined target setting; consideration of these questions is the task of other works.

To "Entertaining Physics", in addition to her second book, adjoins several other works by the same author. One is intended for a relatively unprepared reader who has not yet embarked on a systematic study of physics, and is entitled "Physics at Every Step" (published by "Detizdat"). The other two, on the contrary, mean those who have already completed their secondary school physics course. These are “Entertaining mechanics” and “Do you know physics?”. The last book is, as it were, the end of "Entertaining Physics".

1936 Y. 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 min. 36.8 sec.). To compare with the usual speed of a pedestrian - 1.5 m per second - you need to do a little calculation; then it turns out that the athlete runs 7 m per second. However, these speeds are not quite comparable: a pedestrian can walk for a long time, for hours, doing 5 km per hour, while an athlete is able to maintain a significant speed of his run only a short time. The infantry military unit runs three times slower than the record holder; she does 2 meters per second, or more than 7 kilometers per hour, but she has the advantage over the athlete that she can make much larger transitions.

It is interesting to compare the normal pace of a person with the speed of such - proverbial - slow animals, like a snail or a turtle. The snail fully justifies the reputation attributed to it by the saying: it travels 1.5 mm per second, or 5.4 meters per hour - exactly a thousand times less than a person! Another classically slow animal, the tortoise, does not far outstrip the snail: its usual speed is 70 meters 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 is not far behind the moderate wind. But with a fly flying 5 m per second, a person can compete successfully only on skis. A person will not overtake a hare or a hunting dog even on a horse in a quarry. A person can compete in speed with an eagle only on an airplane.

Often we ask ourselves the question: “Do I have hearing”? Looking into the blue screens of televisions, we see a variety of vocal competitions. And sometimes the winners of these contests don't even have music education, they just have a hearing and a voice, and the rest is attached.

People are usually considered mediocre musically if they cannot distinguish false note from the real one. Those who can not pick up a melody by ear. The very first thing is to sing any melody into a recorder and ask a couple of friends to listen to it. Your friends should be extremely honest. If they say that you "miss" the notes, then most likely you have no hearing. But that's not a problem. Remember that hearing can always be developed.

The next step is to go to a professional. This person should sing and play himself. It is he who can give you the first answers to questions and help you understand what exactly you need to work on in order to develop your ear.

The big problem is that hearing is needed in order to play the musical instruments. You just need to hear where you are playing correctly and where you are wrong.

Determine if there is a rumor

At the moment, there are several ways to check if there is ear for music or not.

• Ask someone who can play the piano to play one note for you. In this case, you do not see which key the person played. Memorize this note by ear. After pressing the piano keys yourself, find this key. If you manage to find the same note, then you have a hearing.
• How to check if a child has hearing? Children are tested for hearing by clapping their hands. Clap the melody with your hands, but not the simplest one, and ask the child to repeat it.
• Pick up a pencil or pen. Your friend should tap out any rhythm with an interval of five to eight seconds. You must repeat this rhythm with great precision. Pauses and duration should be the same.

How to find out if there is a rumor, in a more accurate way?

If you can already play the piano yourself, then the "music test" will suit you. You are played alternately one sound after another in the octave where it is convenient for you to sing. And you have to "get" in unison with the sounds that you hear.

After the tasks described above, you can complicate your task. Notes are played for you, and you must write them down in music book. This is the most accurate way to determine the degree of development of your hearing. But don't worry, over time there won't be a single mistake in your notebook.

The most important thing is not to get upset if your ear for music is not perfect now.

Always work on your improvement. You should always remember that almost all vocal stars developed their abilities through long and hard work.

A professional musician and scientist has developed this music test that tests the musicality of your ear and how good your musical memory. Test your skills in 6 minutes!

You just need to compare pairs of sounds, but what! They are very different, and a lot of nuances are hidden in them. But as a result of this listening test, you will definitely learn something new about yourself.

If you know a little English, you will quickly figure out where to click. If not, use our tips.

When you enter the music test, you will see the following picture:

Click on the arrow!

The music will immediately sound: first one melody, and then the second. Press the green button if the melodies are the same, the red button if they are different. That's all!

At the end of the hearing test, in order to get the most accurate results, you need to provide additional data.

• Number of years you studied music (0 for those who didn't)
• Ethnicity (Caucasian - for Europeans, Mixed - for people with a mixture of nationalities)
• Age
• Gender (male - man, female - woman)
• The result of the hearing test (if you have never been tested - 0)

Women need to additionally answer questions about female cycle, as its characteristics appear to affect hearing.

Put in music test tick one of the 8 options:

• Do you have a regular cycle?
  • I am in menopause
  • I don't have menopause, but I don't have regular periods either.
  • I haven't started my cycle yet (for teenage girls)
• If regular (4 weeks)
  • Now first two week period
  • Now second two week period
• If you are pregnant
  • I'm in first trimester
  • I am in second trimester
  • I'm in third trimester

As a result, you will receive a response like this:

• Above 90%: exceptional ear for music (not even all professional musicians have this)
• Above 80%: very good ear for music (usually this category includes professional musicians)
• Above 70%: normal musical ear
• Above 60%: lower normal
• Above 50%: satisfactory perception of halftones or memory deficit

Scrolling further, you can see the statistics regarding your result ( online translator adapts the answers well into Russian). You will immediately see how good your scores are on the music test compared to other respondents.

You will also see which answers to the listening test turned out to be correct and which were not.

About the ear test and its developer

Although this listening test is simple, it is not at all easy to understand. And all because it was developed by professional musician Jake Mundell, who also works as a radiologist, has a medical degree and is engaged in brain research.

Here is what Jake himself says about his music test:

“While working in the Music and Neuroimaging Laboratory at Harvard’s Beth Israel medical school in Boston, I developed a quick online method for sentiment screening. He actually turned out good test to test your musical ear. The test is deliberately made very difficult, so even professional musicians rarely give more than 80% correct answers. Try it!”

Musical development of the child:
33 answers to parents' questions

Part 1. How to determine the musical ability of a child?

"How do you know if a child has a penchant for music?"
"Does he have an ear for music or a sense of rhythm?"
“Is my child strong enough to learn music?”

In this part, we will discuss five questions related to determining a child's musical ability. The answers to these questions will help parents make a serious choice - whether to send their child to study music or not.

Question 1: How to determine a child's penchant for music?

There are three ways to determine the presence of musicality and talent, the level of development of a child’s musical abilities:

• Conversation with a child
• Determination of the general musicality of the child
• Musical Ability Testing

How to determine the musicality of a child in early childhood, at preschool and primary school age, as well as various ways musical ability testing, we'll go into more detail a bit later. Now, I want to draw your attention to the first way.

Talking to a child seems to be the easiest and most elementary way to find out about his abilities and inclination to music, but in practice it turns out to be very difficult. If you just start asking a child, he is unlikely to answer you with anything intelligible. This should be done between times, specially preparing the situation so that the conversation goes naturally, and does not look like an interrogation. You can talk to him during the game or after listening to children's music, you can not talk specifically, but return to the topic you need from time to time.

Be that as it may, the conversation with the child should serve two purposes.

1) You need to determine the emotionality and artistry of the child- how deeply he can experience artistic images and how vividly, emotionally he can convey them. These qualities are equally important for poetry and for music. Therefore, if your child loves and easily memorizes poetry, reads them with expression, tries to convey the mood - he already has a certain artistry and emotionality. All this is an indicator that the child has a penchant for creativity, he can easily study music and achieve success.

If a child is shy, reads poetry dryly and inexpressively, do not draw critical conclusions! Perhaps your child is an introvert, and the deep feelings that overwhelm him simply do not appear "outside". Perhaps he still "does not know how" to express his emotions and feelings (do it consciously). There can be no single approach, each child will have their own characteristics. But if you see that the child is bored, he does not like not only to talk, but also to listen to poetry, it is difficult for him to remember them - perhaps in this case it is better for you to go in for chess or sports.

So, you can determine the emotionality and artistry of a child by simply asking him to recite his favorite poem.

2) Determine your child's interest in music and creativity. What does he know about music, would he like to do it? What does he like more - singing or playing an instrument? Find out from your child what kind of music he likes best (or more specifically: from which cartoon or movie)? What cartoons or movies does he like to watch and why? What books, about what does he like to read or listen to more? Does he have favorite songs? Ask him to sing one of them.

So you can determine the child's penchant for music, as well as find out what he is interested in in life, understand whether he needs to study music more seriously, go to a music school, or is it enough to attend a music and dance club.

Remember, in order to determine a child's interest in music, it's not so much what he answers (most children of the same age tend to have very similar answers), but how he answers your questions. A certain certainty of the child in his tastes is important. If he doesn't care and he doesn't seem to be particularly enthusiastic about music, you should consider whether musical training the child himself (music classes can captivate him, “open”, but they can also reject him - here everything will depend on the child himself and on the skill of the teacher).

If he can say more or less precisely that he likes cheerful, active music, as in such and such a cartoon; that he loves to sing, dance and play on pillows like drums; he loves cartoons about Spider-Man, because he protects everyone and always defeats “bad monsters”, he loves to read encyclopedias about animals, and his favorite song is “ New Year rushes to us ... ”and not only sings, but also starts dancing ... You have every reason to believe that the child will like to play music and he will be able to achieve certain successes.

Question 2: How to determine the presence of musical abilities in early childhood?

Watching a child (or remembering how he was at this age), you can easily determine whether he has or does not have musical abilities.

The following may indicate that a child has a penchant for music and musical abilities developed from birth:

• increased attention of the child to any sounding background,
• a clear manifestation of interest in the sound of music,
• bright emotional manifestation the joys of the baby while playing his favorite music (some children begin to dance without even learning to walk, sitting in the crib),
• baby loves to listen different music, not only children's and lullabies performed by my mother.

Some time ago, scientists conducted a special study with babies under the age of one year - with the help of simple tests, they found out that most children supposedly have an “absolute” ear for music from birth. This fact confirms the opinion that all people have approximately the same abilities (including musical ones), and only the level of development of these abilities is different for everyone.

This fact also leads to the following conclusion: the mere presence of abilities does not affect the success of a person in a particular field of activity. You can have musical abilities developed from birth - a beautiful, strong voice, perfect pitch and hate music at the same time. Any education, including music, exists in order to develop the necessary abilities in its field and provide certain knowledge. What then is important for success? What is important is the interest, the inclination of a person to a certain field of activity, which allows you to develop abilities in this area faster than other people can do. In most cases, this is the secret of the talent, giftedness of some people and the apparent mediocrity and “lack of ability” of others.

The tendency to a certain field of activity usually manifests itself quite early. The musicality of a child can be detected already at the age of one year, if already at this age he shows a clear interest in the sound of music.

Question 3: How to determine the propensity for music in children at preschool and primary school age?

At this age, all three methods are applicable - talking with the child, testing (we will talk about it a little later), and determining the general musicality of the child.

What are indicators of musicality and the availability of abilities in children aged 3-7 years and older?

1) Maintaining Interest in Music manifested in early childhood. If your child interrupts his business and listens to suddenly sounded music, if he likes to listen to various music, not necessarily only children's songs, but also good pop music, classics, tries to sing along or starts dancing to the music - all this speaks of the musicality of the child.

It should be remembered that raising a child plays big role in this question, but not the main one. If a child is musical by nature, he will show it, no matter if you played music with him or not. If by nature he has no inclination, "thrust" for art, you can "break your forehead", but only develop in the child an aversion to music. All you can do is help your child discover his musicality, give him the opportunity to express himself. If a child showed an interest in music in early childhood, but the parents did not pay attention to it, the child's interest is likely to fade. But this can also happen if you worked hard with your child - sang and learned songs, listened to music, played children's musical instruments. What to do, human nature- a complex and unpredictable thing! :)

2) Your child is easy and for a long time remembers songs he likes. More or less "pure" sings, loves "compose"- compiles some of his songs from words and melodies known to him (in this case, some kind of “potpourri” or something completely unbelievable may come out). Less often - he composes (more precisely, improvises "on the go") his poems and songs - depending on how bright and expressive they turn out (of course, only emotionally, and not in meaning) - one can judge the child's giftedness and the presence of talent. In any case, all this speaks of the musical and creative abilities developed by nature.

3) Does your child love performing in public?, likes to take an active part in matinees and holidays, likes to engage in creativity in any form - sing, dance, draw, sculpt from plasticine. He has a good imagination, he likes to invent - all this is a good indicator of the presence of creativity and music.

Question 4: Does the child have an ear for music?

There are a number of traditional tests to determine musical ear, voice and musical memory. Such tests are usually carried out at an interview when a child is accepted to a music school. These tests are very simple, but they require a minimum set of musical knowledge and skills from parents, and, in some cases, the presence of a piano.

Test 1 Ask the child to come to the piano and turn away. Play two sounds in turn in different registers (upper and lower) and ask him which sound was lower and which was higher.

Test 2 Press one key on the piano and ask the child how many sounds sounded. Now press two keys at the same time (preferably at a great distance from each other), and ask how many sounds have sounded now. If the child finds it difficult to answer, press the same keys in turn. Play any chord with both hands (in a wide range), and ask how many sounds were made (one, or many).

The first two tests check hearing activity, the ability to "navigate in the sound space", to distinguish individual elements from the general sound of music (at the simplest level). They allow you to determine whether the child understands the difference in pitch, as well as the difference between a single sound and several sounded at the same time. If the child finds it difficult - do not worry, it is not so easy to understand these things, usually this is taught in early stage education (preparatory/first grade music school).

Test 3 Sing the note Mi of the first octave (for example, on the syllable "la" or a simple "a") and ask the child to repeat. Then sing the note La of the first octave and again ask to repeat. If you hear that it is difficult for a child to sing in this range, sing the notes higher: Do-Mi of the second octave, or vice versa lower: Small Si - Re of the first octave. Try different notes to determine the range of your child's voice.

It is important that you sing by yourself, without the help of the piano. Use a tuning fork to sing accurately. The fact is that the sound of the piano, as a rule, “knocks down” children, it is more difficult to adapt to it than to what is familiar to them. human voice. If you don't succeed, and it's hard for you to hit the note exactly, it's better, of course, to use the piano. Do not use children's musical instruments - pipes, xylophones, children's synthesizers and others.

Test 4 Sing a simple, short melodic phrase and have your child repeat it. Here are examples of such phrases:

Test 5 Ask your child to sing their favorite song.

So tests 3-5 allow you to check:

• child's ear for music
• musical memory,
• "reproductive" musical ear(can the child repeat the sounded note and melodic phrase),
• child's voice range
• can the child intotone (sing “clearly”).

Remember, if a child shows an average result, if he can catch at least the direction of the melody without hitting the exact note, then he has an ear for music, albeit poorly developed. There are, of course, exceptions, the so-called "hooters". These children can sing in a very narrow range, have no intonation at all and cannot even understand general direction melodies. In fact, there are quite a lot of such children, but in music schools know how to work with them and, in the end, develop their abilities to a certain level (in addition, the inability to sing does not prevent them from being talented pianists or trumpeters).

Question 5: How to determine the sense of rhythm?

Here are some tests for determining the sense of rhythm, which are also used in music schools during opening talk with baby.

Test 1 Tap (not fast) a simple rhythmic sequence and ask the child to repeat. Repeat the test 2-4 times, depending on the child's progress, using different sequences. For example, these:

Test 2 Have your child march in place to the music. Perform or record any popular, marching music. For example, the song "It's fun to walk together ...".

Test 3 Ask your child to clap their hands to the music (as they do at concerts when the audience likes a song). Play or put on a recording of any rhythmic children's music, for example, Letki-Enki.

If a child has a weak sense of rhythm, this does not mean that it cannot be developed. If a child successfully completes all tests, this means that it will be much easier for him to learn music, but this does not guarantee that he will not get bored in a month.

Conclusions:

1) Parents can easily determine the child's inclination to music, the presence of musical abilities and the level of their development in the above ways.

2) Developed musical ability, such as an ear for music or a sense of rhythm, do not mean that a child has a penchant for music. It is the interest, the desire to make music that plays a decisive role in whether the child will achieve success in music or not (it doesn’t matter, on professional level or amateur).

3) The absence of pronounced abilities and a clear desire to study music does not yet give the right to consider a child "incapable", "non-musical". Perhaps it is in the process of learning that the child will reveal his abilities and he will have an interest in music (as they say, appetite comes with eating). Thus, until you start making music with your child, you cannot be completely sure that the child does not have the ability and inclination for music.

To be continued...

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Hello dear readers. On this page you can test your ear for music using the "Online Solfeggio" block. Let's see how it works. In order to test your musical ear - click "Start". You can pre-select one of the five presented keys, as well as a mode. By default, the "note" mode and the key will be in C major.

You can guess one note - the "note" mode, guess five notes - the "test" mode, guess the interval - the "intervals" mode.

rice. 1

By clicking on the "Start" button, either a note or an interval will be played, in accordance with the mode that you have selected. Next, you need to select from the list which note/interval sounded (n) and click on the "Check" button.

If you guessed correctly, the sun sign will be displayed. If you select the test mode, you will be shown how many notes you guessed out of the proposed ones. By pressing the "Again" button, you can take the test again, select a different tone or mode.

You can also enable or disable the display of the correct note or interval in case you guessed wrong (by default - disabled) by clicking on the green square with the note in the lower left corner:

rice. 2

And here is the test itself - good luck.

Note Test Intervals Chords

About intervals

You will hear that the sound of all intervals is different, but you can divide them into several groups - some sound harsh and dissonant - this group is called sharp or dissonances, these include seconds (m2, b2), sevenths (m7, b7) , as well as a tritone (which is called a reduced fifth - mind5 or an increased fourth - uv4). All other intervals are harmonious.

But the latter can also be divided into large-small and clean. Large and small harmonious intervals are thirds and sixths, pure quarts, fifths, octaves (pure ones are also called "empty", since they have a sound neither major nor minor). Large and small, as you remember, differ in their sound - a major third (b3), for example - sounds major (fun) and is the main indicator of the major chord, small (m3) - minor (sad), with sixths also - major (b6 ) - has a major sound small (m6) - minor.

Now that you know how the intervals are distributed by sound, it will be easier for you to navigate in the process of recognizing them by ear.