a hot air balloon is filled with air through an opening
the air is heated using a burner
the hot air causes a pressure on the inside of the balloon
use ideas about molecules to explain how the hot air causes this pressure
The particles of the hot air have a lot of kinetic energy and will bounce around the inside of the hot air balloon knocking into each other and the sides on the balloon. The pressure is caused by the particles knocking into the side of the balloon.
