@Nightmare BunnyHmm ok so for Charle's Law. Let's say you got a glass cube again. This time, the cube is closed off from all sides with no way for us to change its shape, unlike the previous example.
Now, say you got something like a torch or smthing and you put it underneath the glass cube right? The temperature of the glass and the gas inside the glass increases, causing the gas to expand. But, since the volume of the cube cannot change ( can't change its shape ) the pressure of the gas increases instead.
mathematically its something like:
if V = constant then p/T = constant. Charle's law says that the pressure of a certain amount of gas which's Volume is constant is proportional to the absolute temperature of that gas. We measure absolute temperature in Kelvin and we can measure its value using the formula T = 273 + θ where T = temperature, 273 = constant, θ = the temperature measured in Celsius. That means that if you got a temperature of θ=-273C that means that T= 273 + (-273) => T = 0 which is the absolute zero and the lowest temperature that can exist.