mathematics

R or R in number theory represents the real number set in set theory, and the real number part in complex number is also represented by this symbol.

Geometry r or r represents the radius of a circle, and the English word radius.

In geometry, ∠R stands for right angle and the English word right angle.

Geometry r also represents radian (an angle, 360 degrees equals radian 2 π), representing the radian of English words.

Calculus uses the capital R of writing style to express Riemann integral.

physics

Electrical r stands for resistance.

Thermodynamic R stands for three temperature marking methods: Ra stands for Rankine temperature scale, R stands for Leomor temperature scale, and R? r？ Mer temperature scale

R of rotational dynamics is the unit for measuring angular velocity, that is, the amount of rotation per unit time (revolutions, degrees, radians).

Optical R is a unit for measuring X-ray ionizing radiation.

chemistry

R in gas dynamics stands for ideal gas constant.

R in organic chemistry is the general term for hydrocarbon chains.

In stereochemistry, R represents the right-handed (clockwise) molecular arrangement near a carbon atom, and the judgment method is based on the priority rule of Cahn Ingold Prelog.

Biochemical r stands for arginine.

R of chemical reaction represents the molar formation rate per unit volume.

other

Medical R refers to the breathing frequency of people. For example, the r of a normal person is 16 ~ 20 times/minute.

R of computer is an editing language for statistics. Please refer to the r language.

R of a building is a non-metric unit of thermal resistance.

The r of calendar is often used as the abbreviation of Thursday in English to distinguish it from Tuesday with the abbreviation of T.

R in chess stands for Bishop, which is equivalent to the image of China chess.

R of the primary color stands for additive color system, which is red in the three primary color systems of light (red, green and blue).

When driving a vehicle, R is the reverse gear.

The American film industry classifies films according to the Motion Picture Association of America. The R level is equivalent to the restricted level of China people, and it is not suitable for minors to watch.

The legal R is the code name when the court quoted the king (Rex) or queen (Regina) of the country that recognized the British monarch as the head of state.

The International Telecommunication Union (ITC) takes R as the initial code of Russia.

When Japanese Kanji is converted into Roman Pinyin, R is selected instead of L to represent the consonant of the pen name "ら" (line 9).

In Chinese, r refers to the Chinese character "day", which is very common on the Internet.