What period of time is called a day? How many hours, minutes and seconds are there in a day, and why did this happen?
When people say they are “enough with the moment,” they probably don’t realize that they are promising to be free in exactly 90 seconds. Indeed, in the Middle Ages, the term “moment” defined a period of time lasting 1/40 of an hour or, as it was customary to say then, 1/10 of a point, which was 15 minutes. In other words, it totaled 90 seconds. Over the years the moment has lost its original meaning, but is still used in everyday life to denote an indefinite but very short interval.
So why do we remember the moment, but forget about the ghari, the nuctemeron, or something even more exotic?
1. Atom
The word "atom" comes from the Greek term meaning "indivisible", and is therefore used in physics to define the smallest particle of matter. But in the old days this concept was applied to the shortest period of time. A minute was thought to have 376 atoms, each lasting less than 1/6 of a second (or 0.15957 seconds to be precise).
2. Ghari
What kind of instruments and devices were not invented in the Middle Ages to measure time! While Europeans were making full use of hourglasses and sundials, Indians were using clepsydras - ghari. Several holes were made in a hemispherical bowl made of wood or metal, after which it was placed in a pool of water. The liquid, seeping through the slits, slowly filled the vessel until it was completely sank to the bottom from gravity. The whole process took about 24 minutes, which is why this range was named after the device - ghari. At that time it was believed that a day consisted of 60 gharis.
3. Chandelier
Lustre is a period lasting 5 years. The use of this term goes back to antiquity: then lustrum denoted the five-year period of time that completed the establishment of the property qualifications of Roman citizens. When the amount of the tax was determined, the countdown came to an end, and a solemn procession poured out into the streets of the Eternal City. The ceremony ended with lustration (purification) - a pretentious sacrifice to the gods on the Field of Mars, performed for the well-being of citizens.
4. Mileway
All that glitters is not gold. While the light year, seemingly created to define a period, measures distance, mileway, a mile-long path, serves to count time. Although the term sounds like a unit of measurement of distance, in early Middle Ages it designated a segment lasting 20 minutes. This is how long it takes on average for a person to cover a mile-long route.
5. Nundin
Residents Ancient Rome worked seven days a week, tirelessly. On the eighth day, however, which they considered the ninth (the Romans also included the last day of the previous period), they organized huge markets in the cities - nundines. The market day was called “novem” (in honor of November, the ninth month of the 10-month agricultural “Year of Romulus”), and the time interval between the two fairs was called nundin.
6. Nuctemeron
Nuctemerone, a combination of the two Greek words“nyks” (night) and “hemera” (day) are nothing more than an alternative designation for the day we are familiar with. Anything considered nuctemeronic, accordingly, lasts less than 24 hours.
7. Point
IN Medieval Europe a point, also called a dot, was used to indicate the quarter hour.
8. Quadrant
And the neighbor of the point in the epoch, the quadrant, determined a quarter of the day - a period lasting 6 hours.
9. Fifteen
After the Norman Conquest, the word "Quinzieme", translated from French as "fifteen", was borrowed by the British to define the tax, which replenished the state treasury by 15 pence for every pound earned in the country. In the early 1400s, the term also acquired a religious context: it began to be used to indicate an important day church holiday and two full weeks following it. So the “Quinzieme” became a 15-day period.
10. Scrupul
The word "Scrupulus", translated from Latin meaning "small sharp pebble", formerly served as a pharmaceutical unit of weight equal to 1/24 ounce (about 1.3 grams). In the 17th century the scruple, which became symbol small volume, expanded its meaning. It began to be used to indicate 1/60 of a circle (minute), 1/60 of a minute (second) and 1/60 of a day (24 minutes). Now, having lost its former meaning, scruple has been transformed into scrupulousness - attentiveness to detail.
And some more temporary values:
1 attosecond (one billionth of a billionth of a second)
The fastest processes that scientists can time are measured in attoseconds. Using the most advanced laser systems, researchers were able to produce light pulses lasting only 250 attoseconds. But no matter how infinitesimal these time intervals may seem, they seem like an eternity compared to the so-called Planck time (about 10-43 seconds), according to modern science, the shortest of all possible time periods.
1 femtosecond (one millionth of a billionth of a second)
An atom in a molecule vibrates once in a time from 10 to 100 femtoseconds. Even the fastest flowing chemical reaction occurs over a period of several hundred femtoseconds. The interaction of light with the pigments of the retina of the eye, and it is this process that allows us to see our surroundings, lasts about 200 femtoseconds.
1 picosecond (one thousandth of a billionth of a second)
The fastest transistors operate within a time frame measured in picoseconds. The lifetime of quarks, rare subatomic particles produced in powerful accelerators, is only one picosecond. Average duration hydrogen bonding between water molecules at room temperature is three picoseconds.
1 nanosecond (billionth of a second)
A beam of light passing through airless space can cover a distance of only thirty centimeters during this time. Microprocessor in personal computer It will take two to four nanoseconds to execute a single command, such as adding two numbers. The lifetime of the K meson, another rare subatomic particle, is 12 nanoseconds.
1 microsecond (millionth of a second)
During this time, a beam of light in a vacuum will cover a distance of 300 meters, the length of about three football fields. A sound wave at sea level is capable of covering a distance of only one-third of a millimeter in the same period of time. It takes 23 microseconds for a stick of dynamite to explode, the fuse of which has burned to the end.
1 millisecond (thousandth of a second)
The shortest exposure time in a conventional camera. The fly we all know flaps its wings once every three milliseconds. Bee - once every five milliseconds. Every year, the moon orbits the Earth two milliseconds slower as its orbit gradually expands.
1/10 second
Blink an eye. This is exactly what we will be able to do within the specified period. It takes just that long for the human ear to distinguish the echo from the original sound. Spaceship Voyager 1, heading beyond the solar system, moves two kilometers away from the sun during this time. In a tenth of a second, a hummingbird manages to flap its wings seven times.
1 second
The contraction of the heart muscle of a healthy person lasts just this time. In one second, the Earth, rotating around the sun, covers a distance of 30 kilometers. During this time, our star itself manages to travel 274 kilometers, rushing through the galaxy at tremendous speed. Moonlight during this time interval will not have time to reach the Earth.
1 minute
During this time, the newborn baby's brain gains up to two milligrams in weight. A shrew's heart beats 1000 times. An average person can speak 150 words or read 250 words during this time. Light from the sun reaches the Earth in eight minutes. When is Mars at its greatest? close range from the earth, sunlight, reflected from the surface of the Red Planet, reaches us in less than four minutes.
1 hour
This is how long it takes for reproductive cells to split in half. In one hour, 150 Zhiguli cars roll off the assembly line of the Volzhsky Automobile Plant. Light from Pluto - the most distant planet solar system- reaches the Earth in five hours and twenty minutes.
1 day
For people, this is perhaps the most natural unit of time, based on the rotation of the Earth. According to modern science, the length of the day is 23 hours 56 minutes and 4.1 seconds. The rotation of our planet is constantly slowing down due to lunar gravity and other reasons. The human heart makes about 100,000 contractions per day, and the lungs inhale about 11,000 liters of air. During the same time, the baby blue whale gains 90 kg in weight.
1 year
The earth makes one revolution around the sun and rotates on its axis 365.26 times, average level the global ocean rises by 1 to 2.5 millimeters, and 45 federal elections are being held in Russia. It will take 4.3 years for light from the nearby star Proxima Centauri to reach Earth. It will take about the same amount of time for surface ocean currents to go around Earth.
1st century
During this time, the Moon will move away from the Earth by another 3.8 meters, but the giant sea turtle can live as long as 177 years. The lifespan of the most modern CD can be more than 200 years.
1 million years
A spaceship flying at the speed of light will not cover even half the way to the Andromeda galaxy (it is located at a distance of 2.3 million light years from Earth). The most massive stars, blue supergiants (they are millions of times brighter than the sun) burn out in about this time. Due to shifts in the Earth's tectonic layers, North America will move away from Europe by about 30 kilometers.
1 billion years
This is approximately how long it took for our Earth to cool down after its formation. In order for oceans to appear on it, single-celled life would arise and instead of an atmosphere rich in carbon dioxide, an atmosphere rich in oxygen would be established. During this time, the Sun passed four times in its orbit around the center of the Galaxy.
Since the universe has only existed for 12-14 billion years, units of time greater than a billion years are rarely used. However, scientists, specialists in cosmology, believe that the universe may continue even after the last star goes out (in one hundred trillion years) and the last black hole evaporates (in 10,100 years). So the Universe still has a much longer path to go than it has already gone through.
sources
http://www.mywatch.ru/conditions/
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- - [Ya.N.Luginsky, M.S.Fezi Zhilinskaya, Yu.S.Kabirov. English-Russian dictionary of electrical engineering and power engineering, Moscow, 1999] Topics of electrical engineering, basic concepts EN lapse ...
time interval- - [L.G. Sumenko. English-Russian dictionary on information technology. M.: State Enterprise TsNIIS, 2003.] Topics information Technology in general EN time span... Technical Translator's Guide
time interval- laiko tarpas statusas T sritis Standartizacija ir metrologija apibrėžtis Laiko skirtumas tarp dviejų akimirkų. atitikmenys: engl. time interval vok. Zeitintervall, n rus. time interval, m; period of time, m pranc. intervalle de temps, m... Penkiakalbis aiškinamasis metrologijos terminų žodynas
time interval- laiko tarpas statusas T sritis fizika atitikmenys: engl. time interval vok. Zeitintervall, n rus. time interval, m; period of time, m pranc. intervalle de temps, m … Fizikos terminų žodynas
time interval- Syn: interval, term... Thesaurus of Russian business vocabulary
time interval between oscillations- time interval between pulses - [L.G. Sumenko. English-Russian dictionary on information technology. M.: State Enterprise TsNIIS, 2003.] Topics information technology in general Synonyms time interval between pulses EN resting time ... Technical Translator's Guide
time period from inspection to maintenance- — Topics oil and gas industry EN inspection maintenance interval … Technical Translator's Guide
The period of time after which known events return in the same order. In astronomy it is used to mean the time of revolution of a planet or comet. In chronology, in comparison with the cycle, P. denotes a period of time more than... ... encyclopedic Dictionary F. Brockhaus and I.A. Efron
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The basic unit of time is the sidereal day. This is the period of time during which the Earth makes a complete revolution around its axis. When determining sidereal day Instead of the uniform rotation of the Earth, it is more convenient to consider the uniform rotation of the celestial sphere.
A sidereal day is the period of time between two successive culminations of the same name on the point of Aries (or any star) on the same meridian. The beginning of the sidereal day is taken to be the moment of the upper culmination of the Aries point, i.e., the moment when it passes through the midday part of the observer’s meridian.
Due to the uniform rotation of the celestial sphere, the Aries point uniformly changes its hour angle by 360°. Therefore, sidereal time can be expressed by the western hour angle of the Aries point, i.e. S= f y/w.
The hour angle of the Aries point is expressed in degrees and in time. The following ratios serve this purpose: 24 h = 360°; 1 m =15°; 1 m =15"; 1 s =0/2 5 and vice versa: 360°=24 h; 1° = (1/15) h =4 M; 1"=(1/15)*=4 s; 0",1=0 s ,4.
The sidereal day is divided into even smaller units. Finest hour is equal to 1/24 of a sidereal day, a sidereal minute is 1/60 of a sidereal hour and a sidereal second is 1/60 of a sidereal minute.
Hence, sidereal time call the number of sidereal hours, minutes and seconds that have elapsed from the beginning of the sidereal day to a given physical moment.
Sidereal time is widely used by astronomers when making observations at observatories. But this time is inconvenient for everyday human life, which is associated with the daily movement of the Sun.
The diurnal movement of the Sun can be used to calculate time in true solar days. Truly sunny days call the period of time between two successive culminations of the same name of the Sun on the same meridian. The beginning of the true solar day is taken to be the moment of the upper culmination of the true Sun. From here you can get the true hour, minute and second.
The big disadvantage of sunny days is that their duration is not constant throughout the year. Instead of true solar days, average solar days are taken, which are identical in size and equal to the annual average value of true solar days. The word “sunny” is often omitted and they simply say - average day.
To introduce the concept of an average day, an auxiliary fictitious point is used, uniformly moving along the equator and called the average equatorial sun. Its position on the celestial sphere is pre-calculated by the methods of celestial mechanics.
The hour angle of the average sun varies uniformly, and therefore the average day is the same in size throughout the year. Having an idea of the average sun, we can give another definition to the average day. Average day call the period of time between two successive culminations of the same name of the mean sun on the same meridian. The beginning of the average day is taken to be the moment of the lower culmination of the average sun.
The average day is divided into 24 parts - the average hour is obtained. The average hour is divided by 60 to obtain the average minute and, accordingly, the average second. Thus, average time call the number of average hours, minutes and seconds that have passed from the beginning of the average day to a given physical moment. Mean time is measured by the western hour angle of the mean sun. The average day is 3 M 55 s longer than the sidereal day, 9 average time units. Therefore, sidereal time moves forward by about 4 minutes every day. In one month, sidereal time will go by 2 hours compared to the average, etc. Over the course of a year, sidereal time will go forward by one day. Consequently, the beginning of the sidereal day during the year will fall on different time average day.
In navigation manuals and literature on astronomy, the expression “civil mean time”, or more often “mean (civil) time”, is often found. This is explained as follows. Until 1925, the beginning of the average day was taken to be the moment of the upper culmination of the average sun, therefore, the average time was counted from the average noon. Astronomers used this time during observations so as not to divide the night into two dates. In civilian life they used the same average time, but took the average midnight as the beginning of the average day. Such an average day was called a civil average day. The average time measured from midnight was called civil average time.
In 1925, by International Agreement, astronomers adopted civil mean time for their work. Consequently, the concept of average time, counted from the average noon, has lost its meaning. All that remained was civil mean time, which was simplified to be called mean time.
If we denote by T the average (civil) time, and by the -hour angle of the average sun, then T=m+12 H.
Especially important has a connection between sidereal time, the hour angle of a star and its right ascension. This connection is called the basic formula of sidereal time and is written as follows:
The obviousness of the basic formula of time follows from Fig. 86. At the moment of the upper climax t-0°. Then S - a. For the lower climax 5 = 12 H -4+a.
The basic time formula can be used to calculate the hour angle of a star. In fact: r = S+360°-a; let's denote 360° - a = m. Then
The value m is called the stellar complement and is given in the Nautical Astronomical Yearbook. Sidereal time S is calculated from a given moment.
All the times we obtained were counted from an arbitrarily chosen meridian of the observer. That's why they are called local tenses. So, local time is called the time on a given meridian. Obviously, at the same physical moment, the local times of different meridians will not be equal to each other. This also applies to hour angles. Hour angles, measured from an arbitrary meridian of the observer, are called local hour angles; the latter are not equal to each other.
Let us find out the relationships between homogeneous local times and local hour angles of the luminaries on different meridians.
Celestial sphere in Fig. 87 is designed on the equatorial plane; QZrpPn Q" is the observer’s meridian passing through Greenwich. Zrp is the zenith of Greenwich.
Let us additionally consider two more points: one located to the east in longitude LoSt with zenith Z1 and the other to the west in longitude Lw with zenith Z2. Let's plot the point of Aries y, the middle sun O and the luminary o.
Based on the definitions of times and hour angles, then
And
where S GR, T GR and t GR are respectively sidereal time, mean time and hourly angle of the star on the Greenwich meridian; S 1 T 1 and t 1 - sidereal time, mean time and hour angle of the star on the meridian located east of Greenwich;
S 2 , T 2 and t 2 - sidereal time, mean time and hourly angle of the star on the meridian located west of Greenwich;
L - longitude.
Rice. 86.
Rice. 87.
Times and hour angles related to any meridian, as stated above, are called local times and hour angles, then
Thus, homogeneous local times and local hour angles at any two points differ from each other by the difference in longitude between them.
To compare times and hour angles at the same physical moment, the prime (prime) meridian passing through the Greenwich Observatory is adopted. This meridian is called Greenwich.
The times and hour angles assigned to this meridian are called Greenwich times and Greenwich hour angles. Greenwich Mean (civil) time is called Universal (or World) time.
In the relationship between times and hour angles, it is important to remember that to the east the times and western hour angles are always greater than at Greenwich. This feature is a consequence of the fact that the sunrise, sunset and culmination of celestial bodies on the meridians located to the east occur earlier than on the Greenwich meridian.
Thus, the local mean time at different points on the earth's surface will be different at the same physical moment. This leads to great inconvenience. To eliminate this, the entire globe was divided along the meridians into 24 zones. Each zone has the same so-called zone time, equal to the local mean (civil) time of the central meridian. The central meridians are meridians 0; 15; thirty; 45° etc. to the east and west. The boundaries of the belts run in one direction or the other from the central meridian through 7°.5. The width of each belt is 15°, and therefore at the same physical moment the time difference in two adjacent belts is equal to 1 hour. The belts are numbered from 0 to 12 in the eastern and western directions. The belt, the central meridian of which passes through Greenwich, is considered to be the zero belt.
In reality, the boundaries of the belts do not run strictly along the meridians, otherwise it would be necessary to divide some districts, regions and even cities. To eliminate this, borders sometimes follow the borders of states, republics, rivers, etc.
Thus, standard time is called the local, average (civil) time of the central meridian of the zone, accepted as the same for the entire zone. Standard time is designated as TP. Standard time was introduced in our country in 1919. In 1957, due to changes in administrative regions, some changes were made to the previously existing zones.
The relationship between zone time and universal time (Greenwich) TGR is expressed by the following formula:
In addition (see formula 69)
Based on the last two expressions
After the First World War, in different countries, including the USSR, they began to move the clock hand 1 hour or more forward or backward. The transfer was made for a certain period, mostly for the summer and by government order. This time began to be called maternity time T D.
In the Soviet Union, since 1930, by decree of the Council of People's Commissars, the clock hands of all zones were moved forward 1 hour year-round. This was due to economic considerations. Thus, maternity time on the territory of the USSR differs from Greenwich time by the zone number plus 1 hour.
The ship's life of the crew and the ship's dead reckoning are based on the ship's clock, which shows the ship's time T C . Ship's time call the standard time of the time zone in which the ship's clocks are set; it is recorded with an accuracy of 1 minute.
When a ship moves from one zone to another, the hands of the ship's clock are moved 1 hour forward (if the transition is made to the eastern zone) or 1 hour back (if to the western zone).
If at the same physical moment we move away from the zero belt and come to the twelfth belt from the eastern and western sides, then we will notice a discrepancy by one calendar date.
The 180° meridian is considered to be the date line (demarcation line of time). If ships cross this line in an easterly direction (that is, they go on courses from 0 to 180 °), then on the first midnight they repeat the same date. If ships cross it in a westerly direction (that is, they go on courses from 180 to 360°), then one (last) date is omitted at the first midnight.
The demarcation line for the predominant part of its length coincides with the 180° meridian and only in places deviates from it, skirting islands and capes.
A calendar is used to count large periods of time. The main difficulty in creating a solar calendar is the incommensurability of the tropical year (365, 2422 average days) with a whole number of average days. Currently, in the USSR and basically in all states they use the Gregorian calendar. To equalize the length of the tropical and calendar (365, 25 average days) years in the Gregorian calendar, it is customary to count in every four years: three simple years but 365 average days and one leap year - 366 average days each.
Example 36. March 20, 1969 Standard time TP = 04 H 27 M 17 S, 0; A=81°55",0 O st (5 H 27 M 40 C, 0 O st). Determine T gr and T M.
AND THEIR UNITS OF MEASUREMENT
The concept of time is more complex than the concept of length and mass. In everyday life, time is what separates one event from another. In mathematics and physics, time is considered as a scalar quantity, because time intervals have properties similar to those of length, area, and mass.
Time periods can be compared. For example, a pedestrian will spend more time on the same path than a cyclist.
Time periods can be added. Thus, a lecture at an institute lasts the same amount of time as two lessons at school.
Time intervals are measured. But the process of measuring time is different from measuring length, area or mass. To measure length, you can use a ruler repeatedly, moving it from point to point. A period of time taken as a unit can be used only once. Therefore, the unit of time must be a regularly repeating process. Such a unit in the International System of Units is called second. Along with the second, other units of time are also used: minute, hour, day, year, week, month, century. Units such as year and day were taken from nature, and hour, minute, second were invented by man.
Year- this is the time of revolution of the Earth around the Sun.
Day- this is the time the Earth rotates around its axis.
A year consists of approximately 365 days. But a year in a person’s life is made up of a whole number of days. Therefore, instead of adding 6 hours to each year, they add a whole day to every fourth year. This year consists of 366 days and is called leap year.
A week. IN Ancient Rus' the week was called week, and Sunday was called a weekday (when there is no work) or simply a week, i.e. a day of rest. The names of the next five days of the week indicate how many days have passed since Sunday. Monday - immediately after the week, Tuesday - the second day, Wednesday - the middle, the fourth and fifth days, respectively, Thursday and Friday, Saturday - the end of things.
Month- not a very specific unit of time, it can consist of thirty-one days, thirty and twenty-eight, twenty-nine days leap years(days). But this unit of time has existed since ancient times and is associated with the movement of the Moon around the Earth. The Moon makes one revolution around the Earth in about 29.5 days, and in a year it makes about 12 revolutions. These data served as the basis for the creation of ancient calendars, and the result of their centuries-long improvement is the calendar that we use today.
Since the Moon makes 12 revolutions around the Earth, people began to count fuller number revolutions (that is, 22) per year, that is, a year is 12 months.
The modern division of the day into 24 hours also dates back to ancient times; it was introduced in Ancient Egypt. The minute and second appeared in Ancient Babylon, and the fact that there are 60 minutes in an hour and 60 seconds in a minute is influenced by the sexagesimal number system invented by Babylonian scientists.
Time is the most difficult quantity to study. Temporal concepts in children develop slowly in the process of long-term observations, accumulation of life experience, and study of other quantities.
Temporal ideas in first-graders are formed primarily in the process of their practical (educational) activities: daily routine, keeping a nature calendar, perception of the sequence of events when reading fairy tales, stories, when watching movies, daily recording of work dates in notebooks - all this helps the child to see and understand changes in time, feel the passage of time.
Units of time that children are introduced to in elementary school: week, month, year, century, day, hour, minute, second.
Beginning with 1st class, it is necessary to begin comparing familiar time periods that are often encountered in children’s experience. For example, what lasts longer: lesson or recess, school term or winter break; Which is shorter: a student’s school day at school or a parent’s work day?
Such tasks help develop a sense of time. In the process of solving problems related to the concept of difference, children begin to compare the ages of people and gradually master important concepts: older - younger - same in age. For example:
“My sister is 7 years old, and my brother is 2 years older than my sister. How old is your brother?"
“Misha is 10 years old, and his sister is 3 years younger than him. How old is your sister?"
“Sveta is 7 years old, and her brother is 9 years old. How old will each of them be in 3 years?”
In 2nd grade Children form more specific ideas about these periods of time. (2 grades " Hour. Minute " With. 20)
For this purpose, the teacher uses a model of a dial with moving hands; explains that the large hand is called a minute, the small one is called an hour, explains that all watches are designed in such a way that while the large hand moves from one small division to another, time passes 1 min, and while the small arrow moves from one large division to another, it passes 1 hour. Time is counted from midnight to noon (12 noon) and from noon to midnight. Then exercises using the clock model are proposed:
♦ name the designated time (p. 20 No. 1, p. 22 No. 5, p. 107 No. 12)
♦ indicate the time that the teacher or students call.
Different forms of reading the clock are given:
9 hours 30 minutes, 30 minutes past ten, half past ten;
4 hours 45 minutes, 45 minutes past five, 15 minutes to five, quarter to five.
The study of a unit of time is used in solving problems (p. 21 No. 1).
IN 3rd grade children's ideas about such units of time as year, month, week . (3rd class, part 1, p. 9) For this purpose, the teacher uses a report card. Using it, children write down the names of the months in order and the number of days in each month. Immediately, months of equal length are highlighted, marking the shortest month of the year (February). Using the calendar, students determine the serial number of the month:
♦ what is the name of the fifth month of the year?
♦ which month is July?
Set the day of the week, if known, the day and month, and vice versa, set which days of the month certain days of the week fall on:
♦ What dates do Sundays fall on in November?
Using a calendar, students solve problems to find the duration of an event:
♦ how many days does autumn last? How many weeks does it last?
♦ how many days does spring break last?
Concepts about the day is revealed through concepts close to children about the parts of the day - morning, afternoon, evening, night. In addition, they rely on ideas of time sequence: yesterday, today, tomorrow. (3rd grade, part 1, p. 92 “Day”)
Children are asked to list what they were doing from yesterday morning to this morning, what they will do from this evening until tomorrow evening, etc.
"Such periods of time are called for days»
The ratio is set: Day = 24 hours
Then a connection is established with the studied units of time:
♦ How many hours are there in 2 days?
♦ How many days are there in two weeks? In 4 weeks?
♦ Compare: 1 week. * 8 days, 25 hours * 1 day, 1 month. * 35 days.
Later, a unit of time is introduced, such as quarter (every 3 months, 4 quarters in total).
After getting acquainted with the shares, the following problems are solved:
♦ How many minutes is a third of an hour?
♦ How many hours is a quarter of a day?
♦ What part of the year is one quarter?
IN 4th grade ideas about already studied units of time are clarified (part 1, p. 59): a new relationship is introduced -
1 year = 365 or 366 days
Children will learn that the basic units of measurement are day - the time during which the Earth makes a complete revolution around its axis, and year - the time during which the Earth makes a complete revolution around the Sun.
Subject " Time from 0 hours to 24 hours "(P. 60). Children become familiar with the 24-hour counting of time of day. They learn that the beginning of the day is midnight (0 o'clock), that the count of hours during the day starts from the beginning of the day, therefore after noon (12 o'clock) each hour has a different serial number (1 o'clock in the afternoon is 13 o'clock, 2 o'clock days -14 hours...)
Exercise examples:
♦ How to say in another way what time it is:
1) if 16 hours, 20 hours, three quarters of an hour, 21 hours 40 minutes, 23 hours 45 minutes have passed since the beginning of the day;
2) if they said: a quarter to five, half past two, a quarter to seven.
Express:
a) in hours: 5 days, 10 days 12 hours, 120 minutes
b) in a day: 48 hours, 2 weeks
c) in months: 3 years, 8 years and 4 months, a quarter of a year
d) in years: 24 months, 60 months, 84 months.
The simplest cases of addition and subtraction of quantities expressed in units of time are considered. The necessary conversions of time units are performed here along the way, without first replacing the given values. To prevent errors in calculations that are much more complex than calculations with quantities expressed in units of length and mass, it is recommended to give calculations in comparison:
30min 45sec - 20min58sec;
30m 45cm - 20m 58cm;
30c 45kg - 20c 58kg;
♦ With what action can you find out:
1) what time will the clock show in 4 hours if it is now 0 o’clock, 5 o’clock...
2) how long will it take from 14 hours to 20 hours, from 1 hour to 6 hours
3) what time did the clock show 7 hours ago, if now it is 13 hours, 7 hours 25 minutes?
1 min = 60 s
Then the largest of the considered units of time - a century - is considered, and the relationship is established:
Examples of exercises:
♦ How many years are there in 3 centuries? In the 10th centuries? In the 19th centuries?
♦ How many centuries are 600 years? 1100 years? 2000 years?
♦ A.S. Pushkin was born in 1799 and died in 1837. In what century was he born and in what century did he die?
Helps to understand the relationships between units of time table of measures , which should be hung in the classroom for a while, as well as systematic exercises in converting quantities expressed in units of time, comparing them, finding different fractions of any unit of time, solving problems on calculating time.
1st century = 100 in a year 365 or 366 days
1 year = 12 months there are 30 or 31 days in a month
1 day = 24 hours (in February there are 28 or 29 days)
1 hour = 60 minutes
1 min = 60 s
In the topic " Adding and subtracting quantities » the simplest cases of addition and subtraction of composite named numbers expressed in time units are considered:
♦ 18h 36 min -9h
♦ 20 min 30 s + 25 s
♦ 18h 36 min - 9 min (per line)
♦ 5 h 48 min + 35 min
♦2 h 30 min - 55 min
Multiplication cases are considered later:
♦ 2 min 30 s 5
To develop time concepts, we use the solution of problems to calculate the duration of events, their beginning and end.
The simplest problems of calculating time within a year (month) are solved using a calendar, and within a day - using a clock model.
Exercise No. 1
Children are asked to listen to two tape recordings. Moreover, one of them is 20 seconds, and the other is 15 seconds. After listening, children must determine which of the proposed recordings lasts longer than the other. This task causes certain difficulties; children’s opinions differ.
Then the teacher finds out that in order to find out the duration of the melodies, they need to be measured. Questions:
Which of the two melodies lasts longer?
Can this be determined by ear?
What is needed for this. to determine the duration of the melodies.
In this lesson you can enter the hours and unit of time - minute .
Exercise No. 2
Children are invited to listen to two melodies. One of them lasts 1 minute, and the other 55 seconds. After listening, children must determine which melody lasts longer. This task is difficult; children’s opinions differ.
Then the teacher suggests, while listening to the melody, to count how many times the arrow will move. In the process of this work, children find out that when listening to the first melody, the arrow moved 60 times and went a full circle, i.e. the melody lasted one minute. The second melody lasted less, because... While it was sounding, the arrow moved 55 times. After this, the teacher informs the children that each “step” of the arrow is a period of time, which is called second . The arrow, passing a full circle - a minute - takes 60 “steps, i.e. There are 60 seconds in one minute.
Children are offered a poster: “We invite all school students to a lecture on the rules of behavior on the water. The lecture lasts 60.....”
The teacher explains that the artist who drew the poster did not know the units of time and did not write how long the lecture would last. The first grade students decided that the lecture would last 60 seconds, i.e. one minute, and the second grade students decided that the lecture would last 60 minutes. Which one do you think is right? The students find out that the second grade students are right. In the process of solving this problem, children conclude that when measuring periods of time it is necessary to use a single piece of chalk. This lesson introduces a new unit of time measurement - hour .
Why did you decide that the second grade students were right?
What is needed to avoid such errors?
How many minutes in one hour? how many seconds?
The shortest period of time that has physical meaning is the so-called Planck time. This is the time it takes for a photon traveling at the speed of light to overcome the Planck length. The Planck length is expressed, in turn, through a formula in which fundamental physical constants are related - the speed of light, the gravitational constant and Planck's constant. In quantum physics it is believed that at distances smaller than the Planck length the concept of continuous space-time cannot be applied. The length of the Planck time is 5.391 16 (13) 10–44 s.
Greenwich Merchants
John Henry Belleville, an employee of the famous Greenwich Observatory in London, came up with the idea of selling time back in 1836. The essence of the business was that Mr. Belleville checked his watches daily with the most accurate observatory clocks, and then traveled around to clients and allowed them to set the exact time on their watches for money. The service turned out to be so popular that it was inherited by John's daughter, Ruth Belleville, who provided the service until 1940, that is, 14 years after the exact time signals were first broadcast on BBC radio.
No shooting
Modern sprint timing systems have come a long way from the days when the judge fired a pistol and the stopwatch was started manually. Since the result now involves fractions of a second, which is much shorter than human reaction time, electronics rule everything. The pistol is no longer a pistol, but a light-noise device without any pyrotechnics, transmitting the exact start time to the computer. To prevent one runner from hearing the starting signal before another due to the speed of sound, the “shot” is broadcast to speakers installed next to the runners. False starts are also detected electronically, using sensors built into each runner's starting blocks. The finishing time is recorded with a laser beam and a photocell, as well as with the help of an ultra-high-speed camera that captures literally every moment.
A second for billions
The atomic clocks from JILA (Joint Institute for Laboratory Astrophysics), a research center based at the University of Colorado, Boulder, are considered the most accurate in the world. This center is a joint project of the University and National Institute US standards and technologies. In the watch, strontium atoms cooled to ultra-low temperatures are placed in so-called optical traps. The laser causes atoms to vibrate at a rate of 430 trillion vibrations per second. As a result, over 5 billion years the device will accumulate an error of only 1 second.
Atomic Strength
Everyone knows that the most accurate clocks are atomic ones. The GPS system uses atomic clock time. And if wrist watch adjust according to the GPS signal, they will become super accurate. This possibility already exists. The Astron GPS Solar Dual-Time watch, manufactured by Seiko, is equipped with a GPS chipset, which gives it the ability to check the satellite signal and show extremely accurate time anywhere in the world. Moreover, no special energy sources are required for this: Astron GPS Solar Dual-Time is powered only by light energy through panels built into the dial.
Don't anger Jupiter
It is known that on most watches that use Roman numerals on the dial, the fourth hour is indicated by the symbol IIII instead of IV. Apparently, there is a long tradition behind this “substitution”, because there is no exact answer to the question of who came up with the wrong four and why. But there are various legends, for example, that since Roman numerals are the same Latin letters, the number IV turned out to be the first syllable of the name of the very revered god Jupiter (IVPPITER). The appearance of this syllable on the dial sundial The Romans allegedly considered it blasphemy. Everything went from there. Those who don't believe the legends assume it's a matter of design. With the replacement of the 4th century by the 3rd century. The first third of the dial uses only the number I, the second only I and V, and the third only I and X. This way the dial looks neater and more orderly.
A day with dinosaurs
Some people don't have 24 hours in a day, but dinosaurs didn't even have that. In ancient geological times, the Earth rotated much faster. It is believed that during the formation of the Moon, a day on Earth lasted two to three hours, and the Moon, which was much closer, circled our planet in five hours. But gradually lunar gravity slowed down the rotation of the Earth (due to the creation of tidal waves, which are formed not only in water, but also in the crust and mantle), while the orbital momentum of the Moon increased, the satellite accelerated, moved to a higher orbit, where its speed fell. This process continues to this day, and over the course of a century, the day increases by 1/500 s. 100 million years ago, at the height of the age of dinosaurs, the length of the day was approximately 23 hours.
The abysses of time
Calendars in various ancient civilizations were developed not only for practical needs, but also in close connection with religious and mythological views. Because of this, the calendar systems of the past included units of time that far exceeded the life expectancy of a person and even the duration of existence of these civilizations themselves. For example, the Mayan calendar featured time units such as the “baktun”, which was 409 years, as well as epochs of 13 baktuns (5125 years). The ancient Hindus went the furthest - in their sacred texts the period of the universal activity of the Maha Manvantara appears, amounting to 311.04 trillion years. For comparison: the lifespan of the Universe, according to modern science, is approximately 13.8 billion years.
Everyone has their own midnight
Unified systems for calculating time, time zone systems appeared already in the industrial era, and in the old world, especially in its agricultural part, time counting was organized differently in each locality based on observed astronomical phenomena. Traces of this archaism can still be observed today on Mount Athos, in the Greek monastic republic. Clocks are also used here, but midnight is considered the moment of sunset, and the clocks are set to this moment every day. Taking into account the fact that some monasteries are located higher in the mountains, while others are lower, and the Sun for them disappears behind the horizon at different times, then midnight does not come for them all at once.
Live longer - live deeper
The force of gravity slows down the passage of time. In a deep mine, where the gravity of the Earth is stronger, time is running slower than on the surface. And at the top of Mount Everest - faster. The effect of gravitational slowdown was predicted by Albert Einstein in 1907 as part of general theory relativity. It took more than half a century to wait for experimental confirmation of the effect until equipment appeared that could record ultra-small changes over time. Today, the most accurate atomic clocks record the effect of gravitational slowdown when the height changes by several tens of centimeters.
Time - stop!
This effect has long been noticed: if a person’s gaze accidentally falls on a watch dial, then the second hand seems to freeze in place for some time, and its subsequent “tick” seems longer than all the others. This phenomenon is called chronostasis (that is, “time standing”) and, apparently, dates back to the times when our wild ancestor had a vital need to react to any detected movement. When our gaze falls on the arrow and we detect movement, the brain takes a freeze frame for us, and then quickly returns the sense of time to normal.
Time jumps
We, residents of Russia, are accustomed to the fact that the time in all our many time zones differs by a whole number of hours. But outside our country you can find time zones where the time differs from Greenwich by an integer plus half an hour or even 45 minutes. For example, time in India differs from GMT by 5.5 hours, which at one time gave rise to a joke: if you are in London and want to know the time in Delhi, turn your watch over. If you move from India to Nepal (GMT?+?5.45), then the clock will have to be set back 15 minutes, and if you move to China (GMT?+?8), which is right next door, then immediately by 3.5 hours ago!
A watch for every challenge
The Swiss company Victorinox Swiss Army has created a watch that can not only tell the time and withstand the most severe tests (from a fall from a height of 10 m onto concrete to an eight-ton excavator running over it), but also, if necessary, save the life of its owner. They are called I.N.O. X. Naimakka. The bracelet is woven from a special parachute line used to release heavy military equipment, and in difficult situation the wearer can release the bracelet and use the sling in a variety of ways: to pitch a tent, weave a net or snare, lace boots, splint an injured limb, and even start a fire!
Fragrance watch
Gnomon, clepsydra, hourglass- all these names of ancient instruments for keeping time are familiar to us. Less known are the so-called fire clocks, which in their simplest form are a graduated candle. The candle has burned out one notch - say, an hour has passed. The people of the Far East were much more inventive in this regard. In Japan and China there were so-called incense clocks. Instead of candles, sticks of incense smoldered in them, and each hour could have its own aroma. Threads were sometimes tied to the sticks, with a weight attached to the end. At the right moment, the thread burned out, the weight fell onto the sounding plate and the clock struck.
To America and back
The International Date Line runs in the Pacific Ocean, but even there, on many islands, there live people whose lives “between dates” sometimes lead to funny things. In 1892, American traders convinced the king of the island kingdom of Samoa to cross “from Asia to America” by moving east of the date line, which required the islanders to experience the same day, the 4th of July, twice. More than a century later, the Samoans decided to take it all back, so in 2011, Friday, December 30th was abolished. “Residents of Australia and New Zealand will no longer call us during Sunday services, thinking that it’s Monday,” the country’s Prime Minister said on this occasion.
The illusion of the moment
We are accustomed to dividing time into past, present and future, but in a certain (physical) sense, present time is a kind of convention. What's happening in the present? We see the starry sky, but the light from each luminous object takes a different time to reach us - from several light years to millions of years (Andromeda nebula). We see the sun as it was eight minutes ago.
But even if we're talking about about our sensations from nearby objects - for example, from a light bulb in a chandelier or a warm stove that we touch with our hand - it is necessary to take into account the time that passes while the light flies from the light bulb to the retina of the eye or information about sensations moves from the nerve endings to the brain. Everything we experience in the present is a “hodgepodge” of phenomena from the past, distant and near.
Alexander Taranov03.12.2015
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