First, besides balancing the average force \langle \mathscr{F} \rangle and thus sustaining the average pressure \langle P\rangle = \langle \mathscr{F} \rangle /A of the gas, the interaction be...First, besides balancing the average force \langle \mathscr{F} \rangle and thus sustaining the average pressure \langle P\rangle = \langle \mathscr{F} \rangle /A of the gas, the interaction between the heavy piston and the relatively light particles of the gas is weak, because of a relatively short duration of the particle hits (Figure \PageIndex{1}).
