 In this video I'm doing a short simulation here to show an ideal gas when you hold the pressure constant. And that means that from our ratio equations, we're looking at the volume and the temperature relationship. In this case, the way I'm going to do it is I'm actually going to add some heat. And as I add heat, I see that the gas responds by expanding. And if I remove some heat such as the temperature drops, the gas responds by contracting. So if I add heat or cool transfer heat out of the system, not only does the temperature change, but the volume also changes. If I instead of adding heat or subtracting heat directly work with the volume of the gas, I can also see those relationships. If I pull it out, I had to actually add some heat in order to get the pressure to stay the same. Watch what happens down here. I increase my gas, I have to add a little bit of heat to keep the pressure constant. If I compress the gas, I have to actually cool it off, otherwise the pressure would have changed. So the temperature has to change by adding heat or removing heat when I change the volume in order to maintain a constant pressure. As opposed to looking at when I add or subtract heat, how the volume responds to it. But either way, we can use our ratio equations, which I talk about in other videos, to help us understand these relationships.