The main variables that are affected in hot air balloons is the temperature of the air particles inside of the hot air balloon (t).

-The Pressure of the hot air balloon (P) is affected by the temperature of the air particles in the hot air balloon (T). As the temperature increases the pressure increases because the air particles move faster when their temperature is greater causing there to be more collisons and a higher air pressure.

-The Volume of the hot air balloon (V) changes as the pressure inside of the balloon increases to keep the pressure them of the hot air balloon the same (P).  So the volume (V) is constant.

-The number of air particles in the hot air balloon stays the same (n) no air enters or escapes.

-The temperature of the air particles in the hot air balloon (T) is controlled by a bunsen burner in the hot air balloon, the greater the temperature of the air particles the higher the pressure and the balloon rises, and the lower the temperature of the air particles the lower the pressure of the hot air balloon and the balloon sinks.