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Temperature is a physical quantity that quantitatively expresses the attribute of hotness or ... the total number of microstates in the combined system 1 + system 2 ...
is the number of particles (usually atoms or molecules) of the gas. In SI units , p is measured in pascals , V is measured in cubic metres , n is measured in moles , and T in kelvins (the Kelvin scale is a shifted Celsius scale , where 0.00 K = −273.15 °C, the lowest possible temperature ).
Anders Celsius's original thermometer used a reversed scale, with 100 as the freezing point and 0 as the boiling point of water.. In 1742, Swedish astronomer Anders Celsius (1701–1744) created a temperature scale that was the reverse of the scale now known as "Celsius": 0 represented the boiling point of water, while 100 represented the freezing point of water. [5]
In fluid mechanics, the Rayleigh number (Ra, after Lord Rayleigh [1]) for a fluid is a dimensionless number associated with buoyancy-driven flow, also known as free (or natural) convection. [ 2 ] [ 3 ] [ 4 ] It characterises the fluid's flow regime: [ 5 ] a value in a certain lower range denotes laminar flow ; a value in a higher range ...
Mach number is a function of temperature and true airspeed. Aircraft flight instruments, however, operate using pressure differential to compute Mach number, not temperature. Assuming air to be an ideal gas, the formula to compute Mach number in a subsonic compressible flow is found from Bernoulli's equation for M < 1 (above): [9]
For air with a pressure of 1 bar, the Prandtl numbers in the temperature range between −100 °C and +500 °C can be calculated using the formula given below. [2] The temperature is to be used in the unit degree Celsius. The deviations are a maximum of 0.1% from the literature values.
Until 1982, STP was defined as a temperature of 273.15 K (0 °C, 32 °F) and an absolute pressure of exactly 1 atm (101.325 kPa). Since 1982, STP has been defined as a temperature of 273.15 K (0 °C, 32 °F) and an absolute pressure of exactly 10 5 Pa (100 kPa, 1 bar). NIST uses a temperature of 20 °C (293.15 K, 68 °F) and an absolute ...
The "degree Kelvin" (°K) is a former name and symbol for the SI unit of temperature on the thermodynamic (absolute) temperature scale. [1] Since 1967, it has been known simply as the kelvin, with symbol K (without a degree symbol). [2][3][4] Degree absolute (°A) is obsolete terminology, often referring specifically to the kelvin but sometimes ...