StellarGases
Gases are a state of matter defined as having no definite shape or definite volume. In a gas, particles (atoms or molecules) move in all directions. Through the particles moving in all directions, these particles will collide with each other and the surface of the container that the gas is contained in. AP Physics 2 only deals with Ideal Gases, which are gases in which when the particles collide with each other, the collisions are elastic, meaning that both energy and momentum are conserved. If a gas is not ideal, these collisions will make the gas lose energy.