Originally Posted by
mschwett
uh, the force exerted on the object is proportional to its mass, which is why the relationship of force to drag is changed and heavy objects roll downhill faster.
The gravitational force is proportional to mass,
but so is the force required to acheive a certain acceleration so they cancel out and all other things being equal (primarily aero or mechanical drag) then all objects will fall or roll down hill at the same speed. Of course, all other things are not equal.