In a vacuum both the feather and the brick will fall at the same speed. This is because in the absence of air resistance, free-fall acceleration only depends on the mass of the falling body and the acceleration due to gravity. On the other hand, if the objects are subject to air resistance the speed at which they fall will depend on their shape and density.

Shape: The brick has a more streamlined shape than the feather. This means that the air resistance acting on the brick is relatively low, compared to the air resistance acting on the feather. This results in a higher terminal velocity for the brick.

Density: The density of an object is defined as its mass per unit volume. The brick is much denser than the feather. This means that for the same volume of air displaced, the brick is subjected to a greater gravitational force than the feather. This makes the brick fall faster.