i have a rather silly question involving PV = nRT and Charles's Law. Charles's Law states that the volume of a fixed amount of gas maintained at constant pressure is directly proportional to the absolute temperature of the gas. I'm wondering about how do you maintain a constant pressure of the gas?... because when you increase the temperature, the pressure of the gas also wants to increase because the molecules have more kinetic energy. How, in general, do you maintain constant pressure of a gas?