The air surrounding the Earth has mass, and despite the fact that the mass of the atmosphere is about a million times less than the mass of the Earth ( total weight atmosphere is 5.2 * 10 21 g, and 1 m 3 of air at the earth's surface weighs 1.033 kg), this mass of air exerts pressure on all objects located on the earth's surface. The force with which air presses on the earth's surface is called atmospheric pressure.
A column of air weighing 15 tons presses on each of us. Such pressure can crush all living things. Why don't we feel it? This is explained by the fact that the pressure inside our body is equal to atmospheric pressure.
In this way, internal and external pressures are balanced.
Barometer
Atmosphere pressure measured in millimeters mercury(mmHg.). To determine it, they use a special device - a barometer (from the Greek baros - heaviness, weight and metreo - I measure). There are mercury and liquid-free barometers.
Liquidless barometers are called aneroid barometers(from the Greek a - negative particle, nerys - water, i.e. acting without the help of liquid) (Fig. 1).
Rice. 1. Aneroid barometer: 1 - metal box; 2 - spring; 3 - transmission mechanism; 4 — pointer arrow; 5 - scale
Normal atmospheric pressure
Normal atmospheric pressure is conventionally taken to be air pressure at sea level at a latitude of 45° and at a temperature of 0 °C. In this case, the atmosphere presses on every 1 cm 2 of the earth's surface with a force of 1.033 kg, and the mass of this air is balanced mercury column height 760 mm.
Torricelli experience
The value of 760 mm was first obtained in 1644. Evangelista Torricelli(1608-1647) and Vincenzo Viviani(1622-1703) - students of the brilliant Italian scientist Galileo Galilei.
E. Torricelli sealed a long glass tube with divisions at one end, filled it with mercury and lowered it into a cup of mercury (this is how the first mercury barometer was invented, which was called the Torricelli tube). The mercury level in the tube dropped as some of the mercury spilled into the cup and settled at 760 millimeters. A void formed above the column of mercury, which was called Torricelli's void(Fig. 2).
E. Torricelli believed that the atmospheric pressure on the surface of the mercury in the cup is balanced by the weight of the mercury column in the tube. The height of this column above sea level is 760 mm Hg. Art.
Rice. 2. Torricelli experience
1 Pa = 10 -5 bar; 1 bar = 0.98 atm.
High and low atmospheric pressure
Air pressure on our planet can vary widely. If the air pressure is more than 760 mm Hg. Art., then it is considered elevated, less - reduced.
Since the air becomes more and more rarefied as it rises upward, the atmospheric pressure decreases (in the troposphere on average 1 mm for every 10.5 m of rise). Therefore, for territories located on different heights above sea level, the average will be its value of atmospheric pressure. For example, Moscow lies at an altitude of 120 m above sea level, so its average atmospheric pressure is 748 mm Hg. Art.
Atmospheric pressure rises twice during the day (morning and evening) and decreases twice (after noon and after midnight). These changes are due to the change and movement of air. During the year on the continents, the maximum pressure is observed in winter, when the air is supercooled and compacted, and the minimum pressure is observed in summer.
The distribution of atmospheric pressure over the earth's surface has a pronounced zonal character. This is due to uneven heating of the earth's surface, and consequently, changes in pressure.
On globe Three belts with a predominance of low atmospheric pressure (minima) and four zones with a predominance of high atmospheric pressure (maxima) are distinguished.
At equatorial latitudes, the Earth's surface warms up greatly. Heated air expands, becomes lighter and therefore rises. As a result, low atmospheric pressure is established near the earth's surface near the equator.
At the poles, under the influence of low temperatures, the air becomes heavier and sinks. Therefore, at the poles the atmospheric pressure is increased by 60-65° compared to the latitudes.
In the high layers of the atmosphere, on the contrary, over hot areas the pressure is high (although lower than at the Earth's surface), and over cold areas it is low.
General scheme The distribution of atmospheric pressure is as follows (Fig. 3): along the equator there is a belt of low pressure; at 30-40° latitude of both hemispheres - belt high pressure; 60-70° latitude - low pressure zones; in the polar regions there are areas of high pressure.
As a result of the fact that in the temperate latitudes of the Northern Hemisphere in winter the atmospheric pressure over the continents increases greatly, the low pressure belt is interrupted. It persists only over oceans as closed areas low blood pressure— Icelandic and Aleutian minimums. On the contrary, winter maximums form over the continents: Asian and North American.
Rice. 3. General diagram of atmospheric pressure distribution
In summer, in the temperate latitudes of the Northern Hemisphere, the belt of low atmospheric pressure is restored. A huge area of low atmospheric pressure centered in tropical latitudes—the Asian Low—forms over Asia.
In tropical latitudes, the continents are always warmer than the oceans, and the pressure above them is lower. Thus, there are maxima over the oceans throughout the year: North Atlantic (Azores), North Pacific, South Atlantic, South Pacific and South Indian.
The lines that connect points with the same atmospheric pressure on a climate map are called isobars(from the Greek isos - equal and baros - heaviness, weight).
The closer the isobars are to each other, the faster the atmospheric pressure changes over a distance. The amount of change in atmospheric pressure per unit distance (100 km) is called pressure gradient.
The formation of atmospheric pressure belts near the earth's surface is influenced by the uneven distribution of solar heat and the rotation of the Earth. Depending on the time of year, both hemispheres of the Earth are heated by the Sun differently. This causes some movement of the atmospheric pressure belts: in summer - to the north, in winter - to the south.
For normal atmospheric pressure, it is customary to take the air pressure at sea level at a latitude of 45 degrees at a temperature of 0°C. In these ideal conditions a column of air presses on each area with the same force as a column of mercury 760 mm high. This figure is an indicator of normal atmospheric pressure.
Atmospheric pressure depends on the altitude of the area above sea level. At higher elevations, the indicators may differ from ideal, but they will also be considered the norm.
Atmospheric pressure standards in different regions
As altitude increases, atmospheric pressure decreases. So, at an altitude of five kilometers, pressure indicators will be approximately two times less than below.Due to the location of Moscow on a hill, the normal pressure level here is considered to be 747-748 mm column. In St. Petersburg, normal pressure is 753-755 mm Hg. This difference is explained by the fact that the city on the Neva is located lower than Moscow. In some areas of St. Petersburg you can find a pressure norm of an ideal 760 mm Hg. For Vladivostok, normal pressure is 761 mmHg. And in the mountains of Tibet – 413 mmHg.
Impact of atmospheric pressure on people
A person gets used to everything. Even if the indicators normal pressure low compared to the ideal 760 mmHg, but are the norm for the area, people will.A person’s well-being is affected by sharp fluctuations in atmospheric pressure, i.e. decrease or increase in pressure by at least 1 mmHg within three hours
When pressure decreases, a lack of oxygen occurs in a person’s blood, hypoxia of body cells develops, and the heartbeat increases. Headaches appear. There are difficulties from respiratory system. Due to poor blood supply, a person may experience pain in the joints and numbness in the fingers.
Increased pressure leads to an excess of oxygen in the blood and tissues of the body. The tone of blood vessels increases, which leads to their spasms. As a result, the body's blood circulation is disrupted. Visual disturbances may occur in the form of spots before the eyes, dizziness, and nausea. A sharp increase in pressure to large values can lead to rupture of the eardrum.
In which the pressure is balanced by a column of liquid. It is often used as a liquid because it has a very high density (≈13,600 kg/m³) and low saturated vapor pressure at room temperature.
Atmospheric pressure at sea level is approximately 760 mmHg. Art. Standard atmospheric pressure is taken to be (exactly) 760 mmHg. Art. , or 101,325 Pa, hence the definition of a millimeter of mercury (101,325/760 Pa). Previously, a slightly different definition was used: the pressure of a column of mercury with a height of 1 mm and a density of 13.5951·10 3 kg/m³ with a free fall acceleration of 9.806 65 m/s². The difference between these two definitions is 0.000014%.
Millimeters of mercury are used, for example, in vacuum technology, in weather reports and in measuring blood pressure. Since in vacuum technology very often pressure is measured simply in millimeters, omitting the words “mercury column”, the natural transition for vacuum engineers to microns (microns) is carried out, as a rule, also without indicating “mercury column pressure”. Accordingly, when a pressure of 25 microns is indicated on a vacuum pump, we are talking about the maximum vacuum created by this pump, measured in microns of mercury. Of course, no one uses a Torricelli pressure gauge to measure such low pressures. To measure low pressures, other instruments are used, for example, McLeod pressure gauge (vacuum gauge).
Sometimes millimeters of water column are used ( 1 mmHg Art. = 13,5951 mm water Art. ). In the USA and Canada, the unit of measurement “inch of mercury” (designation - inHg) is also used. 1 inHg = 3,386389 kPa at 0 °C.
| Pascal (Pa, Pa) |
Bar (bar, bar) |
Technical atmosphere (at, at) |
Physical atmosphere (atm, atm) |
Millimeter of mercury (mm Hg, mmHg, Torr, torr) |
Water column meter (m water column, m H 2 O) |
Pound-force per sq. inch (psi) |
|
|---|---|---|---|---|---|---|---|
| 1 Pa | 1 / 2 | 10 −5 | 10.197 10 −6 | 9.8692 10 −6 | 7.5006 10 −3 | 1.0197 10 −4 | 145.04 10 −6 |
| 1 bar | 10 5 | 1 10 6 din / cm 2 | 1,0197 | 0,98692 | 750,06 | 10,197 | 14,504 |
| 1 at | 98066,5 | 0,980665 | 1 kgf/cm 2 | 0,96784 | 735,56 | 10 | 14,223 |
| 1 atm | 101325 | 1,01325 | 1,033 | 1 atm | 760 | 10,33 | 14,696 |
| 1 mmHg | 133,322 | 1.3332·10 −3 | 1.3595 10 −3 | 1.3158 10 −3 | 1 mmHg. | 13.595 10 −3 | 19.337 10 −3 |
| 1 m water Art. | 9806,65 | 9.80665 10 −2 | 0,1 | 0,096784 | 73,556 | 1 m water Art. | 1,4223 |
| 1 psi | 6894,76 | 68.948 10 −3 | 70.307 10 −3 | 68.046 10 −3 | 51,715 | 0,70307 | 1 lbf/in 2 |
see also
Wikimedia Foundation. 2010.
- Rodchenko, Alexander Mikhailovich
- Shaikhet, Arkady Samoilovich
See what “Millimeter of mercury” is in other dictionaries:
- (mm Hg, mm Hg), non-system units. pressure; 1 mmHg art. = 133.332 Pa = 1.35952 10 3 kgf/cm2 = 13.595 mm water. Art. Physical encyclopedic dictionary. M.: Soviet encyclopedia. Chief Editor A. M. Prokhorov. 1983. MILLIME... Physical encyclopedia
Non-system units pressure, app. when measuring atm. water vapor pressure, high vacuum, etc. Designation: Russian. - mmHg art., int. — mm Hg. 1 mmHg Art. equal to hydrostatic pressure of a column of mercury with a height of 1 mm and a density of 13.5951... ... Technical Translator's Guide
- – non-system units. pressure; 1 mmHg art. = 133.332 Pa = 1.35952 10 3 kgf/cm2 = 13.595 mm water. Art. [Physical encyclopedia. In 5 volumes. M.: Soviet Encyclopedia. Editor-in-chief A. M. Prokhorov. 1988.] Term heading: General terms... ... Encyclopedia of terms, definitions and explanations of building materials
Off-system unit of pressure; designation: mmHg Art. 1 mmHg Art. = 133.322 Pa = 13.5951 mm water column. * * * MILLIMETER OF MERCURY COLUMN MILLIMETER OF MERCURY, non-systemic unit of pressure; designation: mmHg Art. 1 mmHg Art. = 133.322... encyclopedic Dictionary
Torr, an off-system unit of pressure used when measuring atmospheric pressure of water vapor, high vacuum, etc. Designation: Russian mm Hg. Art., international mm Hg. 1 mm of mercury is equal to hydrostatic... Encyclopedic Dictionary of Metallurgy
- (mmHg) unit of pressure, as a result of which mercury in the column rises by 1 millimeter. 1 mmHg Art. = 133.3224 Pa... Dictionary in medicine
Torr, a non-systemic unit of pressure used in measurements of atmospheric pressure, partial pressure of water vapor, high vacuum, etc. Designations: Russian mm Hg. Art., international mm Hg. 1 mmHg see equal... ... Great Soviet Encyclopedia
Non-system units not subject to use. pressure. Designation mm Hg. Art. 1 mmHg Art. = 133.322 Pa (see Pascal) ... Big Encyclopedic Polytechnic Dictionary
Off-system unit of pressure; designation: mmHg Art. 1 mmHg Art. = 133.322 Pa = 13.5951 mm water. st... Natural science. encyclopedic Dictionary
Weather forecasts often contain atmospheric pressure in mmHg. In science, more conventional units are used - Pascals. Of course, there is a clear connection between them.
Instructions
1. Pascal is the SI unit of pressure. Pascal has the dimension kg/ms². 1 Pascal is a pressure that is a force of 1 Newton per 1 m² of area.
2. 1 mm of mercury is a non-systemic unit of pressure measurement; it is used in relation to the pressure of gases: atmosphere, water vapor, vacuum. The name describes the physical essence of this unit: the pressure on the base of a column of mercury 1 mm high. The precise physical definition of the unit also includes the density of mercury and the acceleration of gravity.
3. 1 mm Hg = 133.322 N/m² or 133 Pa. Thus, if we talk about a pressure of 760 mm Hg, then in Pascals we get the following: 760 * 133.322 = 101325 Pa or approximately 101 kPa.
Pressure– a physical quantity that shows what force acts on a particular surface. Bodies whose substances are in different states of aggregation (solid, liquid and gaseous) exert ideal pressure various methods. For example, if you put a piece of cheese in a jar, it will only press on the bottom of the jar, and milk poured into it acts with force on the bottom and walls of the vessel. In the international measurement system, pressure is measured in pascals. But there are other units of measurement: millimeters of mercury, newtons divided by kilograms, kilo pascals, hecto pascals and so on. The relationship between these quantities is established mathematically.
Instructions
1. The unit of pressure, the pascal, is named after the French scientist Blaise Pascal. It is designated as follows: Pa. When solving problems and in practice, quantities that have multiple or sub-decimal prefixes are applicable. Let's say a kilo pascals, hecto pascals, milli pascals, mega pascals and so on. To convert such quantities into pascals, you need to know the mathematical meaning of the prefix. All available consoles can be found in any physical directory. Example 1. 1 kPa=1000Pa (one kilopascal is equal to one thousand pascals). 1 hPa = 100 Pa (one hectopascal is equal to one hundred pascals). 1 mPa = 0.001 Pa (one millipascal is equal to zero point, one thousandth of a pascal).
2. Pressure Solids are usually measured in pascals. But what is one pascal physically equal to? Based on the definition of pressure, a formula for its calculation is calculated and the unit of measurement is derived. Pressure is equal to the ratio of the force perpendicular to the support to the surface area of this support. p=F/S, where p is pressure measured in pascals, F is force measured in newtons, S is surface area measured in square meters. It turns out, 1 Pa=1N/(m) squared. Example 2. 56 N/(m) squared = 56 Pa.
3. Pressure The air envelope of the Earth is usually called atmospheric pressure and is measured not in pascals, but in millimeters of mercury (hereinafter, mm Hg). In 1643, the Italian scientist Torricelli proposed a skill for measuring atmospheric pressure, which used a glass tube containing mercury (hence “column of mercury”). He also measured that the typical atmospheric pressure is 760 mm Hg. Art., which is numerically equal to 101325 pascals. Then, 1 mm Hg. ~ 133.3 Pa. In order to convert millimeters of mercury to pascals, you need to multiply given value at 133.3. Example 3. 780 mm Hg. Art. = 780*133.3 = 103974 Pa ~ 104 kPa.
In 1960, the International System of Units (SI) came into force, introducing the Newton as a unit of force. It is a “derived unit,” meaning it can be expressed in terms of other SI units. According to Newton's second law, force is equal to the product of a body's mass and its acceleration. Mass in the SI system is measured in kilograms, and acceleration in meters and seconds, therefore 1 Newton is defined as the product of 1 kilogram by 1 meter divided by a second squared.
Instructions
1. Use 0.10197162 to convert to Newtons quantities measured in units called “kilogram-force” (denoted as kgf or kg). Such units are often used in calculations in construction, because they are prescribed in regulatory documents SNiP (" Building codes and rules"). This unit considers the standard gravitational force of the Earth and one kilogram-force can be represented as the force with which a load of one kilogram presses on a scale somewhere on the tier of the sea near the equator of our planet. To convert the famous number kgf to Newtons, it must be divided by the above figure. Let's say 100 kgf = 100 / 0.10197162 = 980.66501 N.
2. Use your math skills and trained memory to do mental calculations to convert quantities measured in kgf to Newtons. If any problems arise with this, then use a calculator - say, the one that Microsoft carefully inserts into the entire distribution of the Windows operating system. To open it, you need to go deeper into the main OS menu into three tiers. First, click the “Start” button to see the items of the first tier, then expand the “Programs” section to access the second, and then go to the “Typical” subsection to the lines of the third tier of the menu. Click the one that says "Calculator".
3. Select and copy (CTRL + C) on this page the conversion rate from kgf to Newtons (0.10197162). After that, switch to the calculator interface and paste the copied value (CTRL + V) - this is easier than manually entering a nine-digit number. Then click the slash button and enter the famous value, measured in kilogram-force units. Click the equal sign button and the calculator will calculate and show you the value of this quantity in Newtons.
Video on the topic
Bar is a unit of pressure measurement that is not part of any system of units. However, it is used in the domestic GOST 7664-61 “Mechanical units”. On the other hand, in our country we use the international SI system, in which a unit called “Pascal” is prepared for measuring pressure. Fortunately, the relationship between them is not difficult to remember, so converting values from one unit of measurement to another is not particularly difficult.
Instructions
1. Multiply the value measured in bars by one hundred thousand to convert this value to Pascals. If the translated value is larger than one, then it is more convenient to use not Pascals, but rather larger derived values from it. Let's say a pressure of 20 bar is equal to 2,000,000 Pascal or 2 megaPascal.
2. Calculate the required value in your head. This shouldn't be difficult because it only requires everyone to move the decimal point in the starting number six places. If, however, any difficulties arise with this operation, you can use online calculators, and even better, online unit converters. For example, this could be a service built into the Google search engine: it combines both a calculator and a converter. To use it, go to the search engine’s website and enter an appropriately defined search query. For example, if you need to convert a pressure value of 20 bar to Pascals, then the request might look like this: “20 bar to Pascals.” After entering the request, it will be sent to the server and processed mechanically, that is, you do not need to press a button to see the result.
3. Use the built-in Windows calculator if you do not have access to the Internet. It also has built-in functions for converting quantities from one unit to another. To launch this application, press the WIN + R key combination, then enter the calc command and press Enter.
4. Expand the “View” section in the calculator menu and select the “Translation of quantities” item in it. In the “Category” drop-down list, select “Pressure”. In the "Initial value" list, set "bar". In the Final Value list, click Pascal.
5. Click the calculator's input field, type the famous value in bars and click the "Convert" button. The calculator will display the equivalent of this value in Pascals in the input field.
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Today there are two measurement systems - metric and non-metric. The latter includes inches, feet and miles, and the metric includes millimeters, centimeters, meters and kilometers. Not metric system measures, as usual, are applied in the USA and the countries of the British Commonwealth. Historically, Americans have found it much easier to measure things in inches than in meters.
Instructions
1. It has long been believed that an inch determines the average length of a phalanx thumb. In the old days, measurements of small objects were usually carried out manually. And so it happened. After this, the inch became the official system of measures in many countries around the world. It is worth noting that the size of an inch in some countries varies within tenths of a centimeter. The English inch size is taken as the generally accepted standard. To convert inches to millimeters, take a calculator and, using the ratio 1 inch = 25.4 millimeters, calculate the length and dimensions of an object in our usual calculation system. To do this, enter a certain number in inches on the calculator, press “multiply” (traditionally, this mathematical parameter corresponds to the * symbol), enter the number 25.4 and press “=”. The numbers that will appear on the monitor screen and will correspond to the length value in millimeters. If you want to convert centimeters to inches, then carry out the same manipulations with the calculator support. Just replace the number 25.4 with 2.54. The last number answers the question how many centimeters are in an inch.
2. If you ever visit an overseas expressway, you will see that distances are measured in miles. And one mile is equal to 1.609344 kilometers. Carry out simple calculations and you will find out the distance to a certain settlement in kilometers. Now, knowing how to convert inches into centimeters and millimeters, you can easily navigate foreign length values. This is doubly significant if, as part of your job, you often come into contact with overseas documentation, where values in inches and feet are widely used. Therefore, in order to quickly navigate these values, always have a calculator with you, one that will help you instantly convert inches to centimeters or millimeters. Traditionally, in everything mobile phone there is a calculator. So you will avoid unnecessary expenses on purchasing an additional computing accessory.
Pascals (Pa, Pa) are the core system unit for measuring pressure (SI). But a multiple unit is used much more often - kilopascal (kPa, kPa). The fact is that one pascal is a very small pressure by human standards. This pressure will be exerted by one hundred grams of liquid evenly distributed over the surface coffee table. If one pascal is compared with atmospheric pressure, then this will be only one hundred thousandth of each.
You will need
- - calculator;
- - pencil;
- - paper.
Instructions
1. To convert the pressure given in pascals to kilopascals, multiply the number of pascals by 0.001 (or divide by 1000). In the form of a formula, this rule can be written as follows: Kkp = Kp * 0.001 or Kkp = Kp / 1000, where: Kkp is the number of kilopascals, Kp is the number of pascals.
2. Example: Typical atmospheric pressure is considered to be 760 mmHg. Art., or 101325 pascals. Question: How many kilopascals is typical atmospheric pressure? Solution: divide the number of pascals by 1000: 101325 / 1000 = 101.325 (kPa). Result: Typical atmospheric pressure is 101 kilopascals.
3. To divide the number of pascals by 1000, easily move the decimal point three digits to the left (as in the example above): 101325 -> 101.325.
4. If the pressure is less than 100 Pa, then to convert it to kilopascals, add the missing insignificant zeros to the number on the left. Example: how many kilopascals will the pressure of one pascal be? Solution: 1 Pa = 0001 Pa = 0.001 kPa. Result: 0.001 kPa.
5. When solving physical problems, keep in mind that pressure can also be specified in other pressure units. Very often when measuring pressure you come across such a unit as N/m? (newton per square meter). In reality, this unit is equivalent to the pascal, because it is its definition.
6. Officially, the unit of pressure pascal (N/m?) is also equivalent to the unit of energy density (J/m?). However, from a physical point of view, these units describe different physical properties. Therefore, do not record the pressure as J/m?.
7. If the task conditions include a lot of other physical quantities, then you convert pascals to kilopascals at the end of solving the problem. The fact is that pascals are a system unit and, if other parameters are indicated in SI units, then the result will be in pascals (of course, if the pressure was determined).
To solve problems correctly, it is necessary to ensure that the units of measurement of quantities correspond to the whole system. Usually, the international measurement system is used to solve mathematical and physical problems. If quantities are specified in other systems, they must be converted to international (SI).
You will need
- – tables of multiples and submultiples;
- - calculator.
Instructions
1. One of the main quantities that are measured in applied sciences is length. Usually it was measured in steps, elbows, transitions, miles, etc. Today the rod unit of length is considered to be 1 meter. Subdivisions of it are centimeters, millimeters, etc. For example, in order to convert centimeters to meters, you need to divide them by 100. If the length is measured in kilometers, convert it to meters by multiplying by 1000. To convert national units of length, use the appropriate indicators.
2. Time is measured in seconds. Other famous units of time are minutes and hours. To convert minutes to seconds, multiply them by 60. Convert hours to seconds by multiplying by 3600. Say, if the time during which an event occurred is 3 hours and 17 minutes, then convert it to seconds in this way: 3?3600+17? 60=11820 s.
3. Speed, as a derived quantity, is measured in meters per second. Another famous unit of measurement is kilometers per hour. To convert the speed to m/s, multiply it by 1000 and divide by 3600. Say, if the speed of a cyclist is 18 km/h, then this value in m/s will be equal to 18? 1000/3600 = 5 m/s.
4. Area and volume are measured respectively in m? them?. When translating, observe the multiplicity of quantities. Let's say, in order to translate cm? in m?, divide their number not by 100, but by 100? = 1000000.
5. Temperature is usually measured in degrees Celsius. But in most problems it needs to be converted into absolute values (Kelvins). To do this, add the number 273 to the temperature in degrees Celsius.
6. The unit of measurement of pressure in the international system is Pascal. But often in technology the unit of measurement is 1 atmosphere. To convert, use the ratio 1 atm.? 101000 Pa.
7. Power in the international system is measured in Watts. Another famous unit of measurement, in particular used for calculating a car engine, is horsepower. To convert values, use the ratio 1 horsepower = 735 watts. Let's say, if a car engine has a power of 86 horsepower, then in Watts it is equal to 86?735=63210 Watts or 63.21 kilowatts.
Pascals measure the pressure that is exerted by a force F on a surface whose area is S. On the contrary, 1 Pascal (1 Pa) is the magnitude of the effect of a force of 1 Newton (1 N) on an area of 1 m2. But there are other units for measuring pressure, one of which is megapascal. Because how to convert megapascals to pascals?
You will need
- Calculator.
Instructions
1. In advance, you need to understand those units of pressure that are between pascal and megapascal. 1 megapascal (MPa) contains 1000 Kilopascals (KPa), 10000 Hectopascals (GPa), 1000000 Decapascals (DaPa) and 10000000 Pascals. This means that in order to convert pascal to megapascal, it is necessary to build 10 Pa to the power of “6” or multiply 1 Pa by 10 seven times.
2. In the first step it became clear what to do in order to complete direct action to the transition from small units of pressure measurement to larger ones. Now, in order to do the opposite, you will need to multiply the existing value in megapascals by 10 seven times. On the contrary, 1 MPa = 10,000,000 Pa.
3. For greater simplicity and clarity, let us look at an example: in an industrial propane cylinder, the pressure is 9.4 MPa. How many Pascals will this same pressure be? Solving this problem requires using the above method: 9.4 MPa * 10000000 = 94000000 Pa. (94 million Pascals). Result: in an industrial cylinder, the pressure of propane on its walls is 94,000,000 Pa.
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Note!
It is worth noting that much more often it is not the classical unit of pressure measurement that is used, but the so-called “atmosphere” (atm). 1 atm = 0.1 MPa and 1 MPa = 10 atm. For the example discussed above, another result will be objective: the propane pressure of the cylinder wall is 94 atm. It is also acceptable to use other units, such as: - 1 bar = 100,000 Pa - 1 mmHg (millimeter of mercury) = 133.332 Pa - 1 m of water. Art. (meter of water column) = 9806.65 Pa
Helpful advice
Pressure is denoted by the letter P. Based on the information given above, the formula for finding pressure will look like this: P = F/S, where F is the force acting on the area S. Pascal is the unit of measurement used in the SI system. In the SGS system (“Centimeter-Gram-Second”), pressure is measured in g/(cm*s?).
The density of mercury, at room temperature and typical atmospheric pressure, is 13,534 kilograms per cubic meter or 13.534 grams per cubic centimeter. Mercury is the densest of all currently known liquids. It is 13.56 times denser than water.
Density and its units of measurement
Density or volumetric density of a substance is the mass of this substance per unit volume. More often than not, the Greek letter rho - ? is used to designate it. Mathematically, density is determined by the ratio of mass to volume. In the International System of Units (SI), density is measured in kilograms per cubic meter. That is one cubic meter mercury weighs 13 and a half tons. In the previous SI system, CGS (centimeter-gram-second), it was measured in grams per cubic centimeter. IN traditional systems units still in use in the United States and inherited from the British Imperial system of units, density can be expressed in ounces per cubic inch, pounds per cubic inch, pounds per cubic foot, pounds per cubic yard, pounds per gallon, pounds per bushel and others . To facilitate comparison of densities between different systems units, sometimes it is indicated as a dimensionless quantity - relative density. Relative density is the ratio of the density of a substance to a certain standard, as usual, to the density of water. Thus, a relative density less than one means that the substance floats in water. Substances with a density less than 13.56 will float in mercury. As we can see in the picture, a coin made of a metal alloy with a relative density of 7.6 floats in a container of mercury. Density depends on temperature and pressure. As pressure increases, the volume of the material decreases and, consequently, the density increases. As the temperature increases, the volume of the substance increases and the density decreases.
Some properties of mercury
The ability of mercury to change density when heated was discovered by use in thermometers. As temperature increases, mercury expands more evenly than other liquids. Mercury thermometers can be used to measure wide range temperatures: from -38.9 degrees, when mercury freezes, to 356.7 degrees, when mercury boils. It is easy to raise the upper limit of measurements by increasing the pressure. In a medical thermometer, due to high density mercury, the temperature remains exactly at the same level as it was in the patient’s armpit or in another place where the measurement was taken. When the mercury reservoir of a thermometer cools, some of the mercury still remains in the capillary. They drive the mercury back into the reservoir by vigorously shaking the thermometer, giving the heavy column of mercury an acceleration many times greater than the acceleration of free flight. True, now medical institutions in a number of countries are trying to abandon mercury thermometers. The reason is the toxicity of mercury. Once in the lungs, mercury vapor lingers there for a long time and poisons every organism. The typical functioning of the central nervous system and kidneys is disrupted.
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Note!
Atmospheric pressure is measured using a barometer, in which a column of mercury is present. In addition to these 2 units, there are other units: bars, atmospheres, mm of water column, etc. 1 mm of mercury is also called torr.
Note, there are 2 tables and a list. Here's another useful link:
| In units: | |||||||||
| Pa (N/m2) | MPa | bar | atmosphere | mmHg Art. | mm in.st. | m in.st. | kgf/cm 2 | ||
| Should be multiplied by: | |||||||||
| Pa (N/m2) | 1 | 1*10 -6 | 10 -5 | 9.87*10 -6 | 0.0075 | 0.1 | 10 -4 | 1.02*10 -5 | |
| MPa | 1*10 6 | 1 | 10 | 9.87 | 7.5*10 3 | 10 5 | 10 2 | 10.2 | |
| bar | 10 5 | 10 -1 | 1 | 0.987 | 750 | 1.0197*10 4 | 10.197 | 1.0197 | |
| atm | 1.01*10 5 | 1.01* 10 -1 | 1.013 | 1 | 759.9 | 10332 | 10.332 | 1.03 | |
| mmHg Art. | 133.3 | 133.3*10 -6 | 1.33*10 -3 | 1.32*10 -3 | 1 | 13.3 | 0.013 | 1.36*10 -3 | |
| mm in.st. | 10 | 10 -5 | 0.000097 | 9.87*10 -5 | 0.075 | 1 | 0.001 | 1.02*10 -4 | |
| m in.st. | 10 4 | 10 -2 | 0.097 | 9.87*10 -2 | 75 | 1000 | 1 | 0.102 | |
| kgf/cm 2 | 9.8*10 4 | 9.8*10 -2 | 0.98 | 0.97 | 735 | 10000 | 10 | 1 | |
| 47.8 | 4.78*10 -5 | 4.78*10 -4 | 4.72*10 -4 | 0.36 | 4.78 | 4.78 10 -3 | 4.88*10 -4 | ||
| 6894.76 | 6.89476*10 -3 | 0.069 | 0.068 | 51.7 | 689.7 | 0.690 | 0.07 | ||
| Inches Hg / inches Hg | 3377 | 3.377*10 -3 | 0.0338 | 0.033 | 25.33 | 337.7 | 0.337 | 0.034 | |
| Inches in.st. / inchesH2O | 248.8 | 2.488*10 -2 | 2.49*10 -3 | 2.46*10 -3 | 1.87 | 24.88 | 0.0249 | 0.0025 | |
| To convert pressure in units: | In units: | |||
| psi pound square feet (psf) | psi inch / pound square inches (psi) | Inches Hg / inches Hg | Inches in.st. / inchesH2O | |
| Should be multiplied by: | ||||
| Pa (N/m2) | 0.021 | 1.450326*10 -4 | 2.96*10 -4 | 4.02*10 -3 |
| MPa | 2.1*10 4 | 1.450326*10 2 | 2.96*10 2 | 4.02*10 3 |
| bar | 2090 | 14.50 | 29.61 | 402 |
| atm | 2117.5 | 14.69 | 29.92 | 407 |
| mmHg Art. | 2.79 | 0.019 | 0.039 | 0.54 |
| mm in.st. | 0.209 | 1.45*10 -3 | 2.96*10 -3 | 0.04 |
| m in.st. | 209 | 1.45 | 2.96 | 40.2 |
| kgf/cm 2 | 2049 | 14.21 | 29.03 | 394 |
| psi pound square feet (psf) | 1 | 0.0069 | 0.014 | 0.19 |
| psi inch / pound square inches (psi) | 144 | 1 | 2.04 | 27.7 |
| Inches Hg / inches Hg | 70.6 | 0.49 | 1 | 13.57 |
| Inches in.st. / inchesH2O | 5.2 | 0.036 | 0.074 | 1 |
Detailed list of pressure units:
- 1 Pa (N/m 2) = 0.0000102 Atmosphere (metric)
- 1 Pa (N/m2) = 0.0000099 Atmosphere (standard) = Standard atmosphere
- 1 Pa (N/m2) = 0.00001 Bar / Bar
- 1 Pa (N/m 2) = 10 Barad / Barad
- 1 Pa (N/m2) = 0.0007501 Centimeters Hg. Art. (0°C)
- 1 Pa (N/m2) = 0.0101974 Centimeters in. Art. (4°C)
- 1 Pa (N/m2) = 10 Dyne/square centimeter
- 1 Pa (N/m2) = 0.0003346 Foot of water (4 °C)
- 1 Pa (N/m2) = 10 -9 Gigapascals
- 1 Pa (N/m2) = 0.01
- 1 Pa (N/m2) = 0.0002953 Dumov Hg. / Inch of mercury (0 °C)
- 1 Pa (N/m2) = 0.0002961 InchHg. Art. / Inch of mercury (15.56 °C)
- 1 Pa (N/m2) = 0.0040186 Dumov v.st. / Inch of water (15.56 °C)
- 1 Pa (N/m 2) = 0.0040147 Dumov v.st. / Inch of water (4 °C)
- 1 Pa (N/m 2) = 0.0000102 kgf/cm 2 / Kilogram force/centimetre 2
- 1 Pa (N/m 2) = 0.0010197 kgf/dm 2 / Kilogram force/decimetre 2
- 1 Pa (N/m2) = 0.101972 kgf/m2 / Kilogram force/meter 2
- 1 Pa (N/m 2) = 10 -7 kgf/mm 2 / Kilogram force/millimeter 2
- 1 Pa (N/m 2) = 10 -3 kPa
- 1 Pa (N/m2) = 10 -7 Kilopound force/square inch
- 1 Pa (N/m 2) = 10 -6 MPa
- 1 Pa (N/m2) = 0.000102 Meters w.st. / Meter of water (4 °C)
- 1 Pa (N/m2) = 10 Microbar / Microbar (barye, barrie)
- 1 Pa (N/m2) = 7.50062 Microns Hg. / Micron of mercury (millitorr)
- 1 Pa (N/m2) = 0.01 Millibar / Millibar
- 1 Pa (N/m2) = 0.0075006 Millimeter of mercury (0 °C)
- 1 Pa (N/m2) = 0.10207 Millimeters w.st. / Millimeter of water (15.56 °C)
- 1 Pa (N/m2) = 0.10197 Millimeters w.st. / Millimeter of water (4 °C)
- 1 Pa (N/m 2) = 7.5006 Millitorr / Millitorr
- 1 Pa (N/m2) = 1N/m2 / Newton/square meter
- 1 Pa (N/m2) = 32.1507 Daily ounces/sq. inch / Ounce force (avdp)/square inch
- 1 Pa (N/m2) = 0.0208854 Pounds of force per square meter. ft / Pound force/square foot
- 1 Pa (N/m2) = 0.000145 Pounds of force per square meter. inch / Pound force/square inch
- 1 Pa (N/m2) = 0.671969 Poundals per sq. ft / Poundal/square foot
- 1 Pa (N/m2) = 0.0046665 Poundals per sq. inch / Poundal/square inch
- 1 Pa (N/m2) = 0.0000093 Long tons per square meter. ft / Ton (long)/foot 2
- 1 Pa (N/m2) = 10 -7 Long tons per square meter. inch / Ton (long)/inch 2
- 1 Pa (N/m2) = 0.0000104 Short tons per square meter. ft / Ton (short)/foot 2
- 1 Pa (N/m2) = 10 -7 Tons per sq. inch / Ton/inch 2
- 1 Pa (N/m2) = 0.0075006 Torr / Torr
