What is Cold: Definition and 394 Discussions

Cold is the presence of low temperature, especially in the atmosphere. In common usage, cold is often a subjective perception. A lower bound to temperature is absolute zero, defined as 0.00 K on the Kelvin scale, an absolute thermodynamic temperature scale. This corresponds to −273.15 °C on the Celsius scale, −459.67 °F on the Fahrenheit scale, and 0.00 °R on the Rankine scale.
Since temperature relates to the thermal energy held by an object or a sample of matter, which is the kinetic energy of the random motion of the particle constituents of matter, an object will have less thermal energy when it is colder and more when it is hotter. If it were possible to cool a system to absolute zero, all motion of the particles in a sample of matter would cease and they would be at complete rest in this classical sense. The object would be described as having zero thermal energy. Microscopically in the description of quantum mechanics, however, matter still has zero-point energy even at absolute zero, because of the uncertainty principle.

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  1. D

    If you lie on the ground at night with no cover, you get cold rather

    If you lie on the ground at night with no cover, you get cold rather quickly. Much of this is due to energy loss by radiation. At night in a dry climate, the temperature of the sky can drop to -40oC. If you are lying on the ground with thin clothing that provides little insulation, the surface...
  2. S

    I'm looking for some cold propulsion possibilities

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  3. Spinnor

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  4. H

    Cold shutdown that doesn't require coolant circulation?

    "cold shutdown" that doesn't require coolant circulation? I was wondering what is preventing a plant being built that can be truly shut down and not require coolant circulation. Is it that efficiency would be reduced to unacceptable levels?
  5. G

    Does Wind Feel Cold Because of Heat Transfer?

    You now how when you feel a light breeze it feels kind of cool? Why? Atoms are moving faster and they hit your skin with higher velocity so I would think wind would be hotter than normal.
  6. M

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  7. Q

    Will the expanding universe really end up cold and empty?

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  8. H

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  9. A

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  10. M

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  11. J

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  12. neduet

    Hot water is heavier than cold water.

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  13. B

    Medical Which has better health benefits, hot tea or cold tea?

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  14. J

    Does cold gasoline have less energy

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  15. hxtasy

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  16. P

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  17. A

    When an object becomes very cold do the electrons stop revolving ?

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  18. R

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  19. A

    Cold War Books & Movies: Find Your Next Read/Watch!

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  20. V

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  21. C

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  22. C

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  23. B

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  24. Orion1

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  25. C

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  26. T

    News Another cold war ? China and U.S.

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  27. P

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  28. E

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  29. Pengwuino

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  30. S

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  31. R

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  32. M

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  33. U

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  34. C

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  35. W

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  36. H

    Why does the weight of opened cold coke change over time?

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  37. E

    Concerned that engineering might be cold and indifferent?

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  38. larrybud

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  39. C

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  40. Pengwuino

    Crave Cold Water? Refreshingly Satisfy with an Ice-Cold Glass!

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  41. A

    Thermal - why check tire pressure when it's cold?

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  42. K

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  43. W

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  44. W

    News Was Defense a lie during the Cold War?

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  45. N

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  46. C

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  47. C

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  48. R

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  49. Q

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  50. O

    Heat & Cold: Atomic Level & Beyond

    What is heat and cold in the atomic scale? Why do things sometimes feel hot and sometimes cold?
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