I think that Neil Armstrong's experiment and videos on the moon say it all. The hammer and the feather fell at the same time and hit at the same time when on the moon. They "should" fall at the same rate of acceleration... or should they?
We have a slight problem Huston. The moon has much less air resistance than earth. Most chunks of iron would be assembled in such a way to have lower air resistance than the feathers. The force of the air will not slow down the iron and therefore it will, on a planet with a reasonable amount of atmosphere, accelerate to the ground more quickly.
But wait... there's more!
That's right. For today only we will provide you with 3 answers for the price of one! (Unlike the TV ads I will also give out free shipping. For today only!)
If you create a structure that can withstand a vacuum and hold both objects they can fall at the same rate on earth. Place the objects in a clamp at the top of the container, remove the air, drop the items and see which hits first.
"Both," you say?
My dear Sir, you are correct.
So then, which falls faster? The chicken... oh wait wrong answer...
Which accelerates towards earth at a greater pace? Neither or iron is the correct answer due to the variances in air resistance.