In an example problem in Section 13.2 we considered leakage from a flexible party balloon. If the leakage is from a rigid container (a metal storage tank, for example), the number of atoms per cubic...

In an example problem in Section 13.2 we considered leakage from a flexible party balloon. If the leakage is from a rigid

container (a metal storage tank, for example), the number of atoms per cubic meter, n, will decrease with time t. If the total

volume of the tank is V, there are N = nV atoms in the tank at any instant, so we can write the following “differential”

equation (that is, an equation that involves derivatives):