Buoyancy is functionally irrelevant here. Buoyancy in air effectively subtracts 1.3kg per cubic meter of each substance: The mass of the volume of air displaced by the object.
The part you are not understanding: Drag applies the same force to both objects. Gravity applies the same acceleration to each object.
That is incorrect. Drag affects both equally. The difference is caused by buoyancy, less dense objects feel more buoyancy
If F is the same but m is different, what happens to a?
Buoyancy is functionally irrelevant here. Buoyancy in air effectively subtracts 1.3kg per cubic meter of each substance: The mass of the volume of air displaced by the object.
The part you are not understanding: Drag applies the same force to both objects. Gravity applies the same acceleration to each object.
Thanks that does make sense