How can a compression of gas molecules change their velocity therefore their KE? My intuition suggest me that there should be a change of mean molecule path length and so the frequency they hit the container should rise and that should be the cause of greater pressure. Can we compare this with a tunnel with a particle oscillating between the two entrances of the tunnel. When we shrink the tunnel length the particle should hit the entrances more frequently.Let say we move a wall against them... they will gain twice the velocity of the wall as it ca be considered as infinite mass in comparision with the molecules and if we count how many times the molecule intercts with the moving wall during motion of the wall we get the incease of velocity. So greater the frequency of collisions with the wall the greater the change in velocity of the molecule?