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## Homework Statement

An ideal gas with molecules of mass m is contained in a cube with sides of area A. The pressure exerted by the gas on the top of the cube is P, and N molecules hit the top of the cube in a time

Δt. What is the average vertical component of the velocity of the gas molecules.

## Homework Equations

F = ma P = f/A

## The Attempt at a Solution

F = ma

F = mΔV /Δt

F = 2mV / Δt (ΔV = 2V since collisions are elastic)

Putting this into P = F/A leads to the correct answer but my problem is with the Δt. When used in the acceleration Δt should be the time that the molecules is in contact with the wall of the container and it seems to me to be unrelated to the Δt as specified in the question.

Thanks to anybody that can help clear this up.