That's our assumption. So eventually, some of these molecules will hit the walls of the container. At any given time, some of these molecules will hit the wall at exactly the spot where this hole is, and they will exit or escape the cube. What this formula tells us is that the higher your velocity is, the more likely that you will collide with the wall at this position, at this point in time, and the more likely you will escape into the vacuum. So we can rewrite these velocities as rates. So the rate of effusion for gas one divided by the rate of infusion for gas two is equal to the square root of mass one divided by the square root of mass two.