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QUESTION: why we not assumed that all gas molecules have same speed as their collision is elstic

ANSWER: The fact that the collisions are elastic does not mean that the velocities are the same! Momentum must also be conserved and the masses of the particles are also different.

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QUESTION: if the mass of every particle is same then there is  any transfer of kinetic energy between particles? we assumed that the gas molecules have same mass

In fact, the molecules will follow a "normal" type distribution with some particles moving very fast while others move very slowly with the majority moving near the center of the distribution. This is why water evaporates at room temperature where even though the temperature may be well below the boiling point, some of the molecules have much higher energies than the average and can leave the surface of the water even though the water is room temperature.


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James J. Kovalcin


I am teaching or have taught AP physics B and C [calculus based mechanics & electricity and magnetism] as well as Lab Physics for college bound students. I have a BS in Physics from the University of Pittsburgh and a Master of Arts in Teaching from same. I have been teaching physics for 34 years. I am constantly updating my skills and have a particular interest in modern physics topics.

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