After the test on the ideal gas model, we started talking about the four assumptions of our ideal gas model. We'll assume a steady state; we're not going to talk about pipes as they fill up with water. We'll also assume incompressibility, that we can't fit more fluid into a space by applying more pressure. This means the model, from now on, doesn't include gases, but that's OK. Now we can explain why, when water comes out the tap or oil pours from a bottle, the stream gets thinner as it falls. We came up with the concept of volume flow rate, which we'll practice tomorrow.