What does “Temperature and molecular kinetic energy” actually mean in Kinetic Theory of Gases, and why does it matter for JEE?
For an ideal gas, absolute temperature measures average translational kinetic energy per molecule: 3k_BT/2. At the same temperature, light and heavy molecules have the same average translational energy but different rms speeds.
In simple words: For an ideal gas, absolute temperature measures average translational kinetic energy per molecule: 3k_BT/2. At the same temperature, light and heavy molecules have the same average translational energy but different rms speeds. Getting Temperature and molecular kinetic energy clear matters because JEE questions on Kinetic Theory of Gases usually test this idea directly, not just a formula you memorised.
Key point
Temperature and molecular kinetic energy
Common mistake
saying every molecule has the same speed at a given temperature.
Memory tip
same average energy, lighter molecules move faster.
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