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The thermal velocity or thermal speed is a typical velocity of the thermal motion of particles which make up a gas, liquid, etc. Thus, indirectly, thermal velocity is a measure of temperature. Technically speaking it is a measure of the width of the peak in the Maxwell–Boltzmann particle velocity distribution. Note that in the strictest sense ''thermal velocity'' is not a velocity, since ''velocity'' usually describes a vector rather than simply a scalar speed. Since the thermal velocity is only a "typical" velocity, a number of different definitions can be and are used. Taking to be the Boltzmann constant, is the temperature, and is the mass of a particle, then we can write the different thermal velocities: == In one dimension == If is defined as the root mean square of the velocity in any one dimension (i.e. any single direction), then :. If is defined as the mean of the magnitude of the velocity in any one dimension (i.e. any single direction), then :. If is defined as the half-width of the thermal distribution or if is defined such that a particle with this speed has an energy of , then :. By all of these definitions falls in the range of :. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「thermal velocity」の詳細全文を読む スポンサード リンク
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