# If three ideal gases collide with each other, how will the second one travel?

Sep 9, 2017

With accelerated velocity.

An ideal gas is considered to be a point mass with negligible volume compared to its container. So, we neglect all degrees of freedom but those of linear motion. As a result, we assume the gas does not rotate or vibrate, but only moves in a straight line.

However, they are also said to collide elastically, i.e. perfect transfer of kinetic energy ($K = \frac{1}{2} m {v}^{2}$).

As a result, an ideal gas in the middle of two others receives additional kinetic energy, which goes into increasing its velocity.

(If you closely in the above diagram, that is precisely what occurs.)

Thus, an ideal gas that was hit by another one, that consequently collides into a third, had traveled with an accelerated velocity imparted by the first ideal gas.