The thermodynamic scale is built so that it does not depend on any particular material. Its zero point and its simple link to Celsius are the two facts to hold on to.
The thermodynamic (Kelvin) scale does not depend on the substance used. Its zero, absolute zero (0 K = −273.15 °C), is where particles have least kinetic energy, and T / K = θ / °C + 273.15.
Many properties change with temperature, but two thermometers using different properties need not agree between their fixed points. The thermodynamic scale avoids this by being defined without reference to any substance. In the simulation the particles slow as the temperature falls and freeze at absolute zero, 0 K.
The Celsius scale is the thermodynamic scale shifted: T / K = θ / °C + 273.15. The size of one kelvin equals the size of one degree Celsius, so temperature differences are the same on both. Absolute zero, 0 K = −273.15 °C, is the temperature at which particles have their minimum kinetic energy; it cannot be reached.
Four quick checks on conversion, absolute zero and why the scale is substance-independent. Each correct answer earns XP and lights this skill on your star map.
To convert a temperature in degrees Celsius to the thermodynamic (kelvin) scale you:
Absolute zero is:
An advantage of the thermodynamic temperature scale over one based on the expansion of a liquid is that it:
A temperature change of 1 K is the same as a temperature change of:
Kelvin takes no degree symbol and is never negative for a real temperature. Because only the zero point differs from Celsius, a temperature difference is the same number on both scales, so in Q = mcΔθ you may use Δθ in K or in °C. Absolute zero marks the minimum particle kinetic energy and cannot actually be reached.
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