Why will a 15 pound bowling ball and a 3 pound horseshoe dropped from the same height both hit the ground at the same time?

Answer 1

Because while a larger mass has a proportionally greater inertia (resistance to movement) than a smaller one, the pull of gravity also affects it that much more. The net result is to exactly cancel out the forces, allowing all objects within a given gravitational field (regardless of their mass) to fall at the same rate... unless there's another force, like air resistance on a feather, to tip the balance.

Answer 2

As a disclaimer, I am not a scientist nor a physicist... but this answer should suffice for those looking for a general answer.

These objects will hit the ground at the same time. Here's why I believe that to be true for the casual observer: both object are more or less not affected by the resistance offered by the air they will fall through, especially at a distance of 3 feet, thus, they hit the ground at the same time.

If one of the objects was light enough or otherwise affected by air (such as a feather or a sheet of paper), then they may not since air will tend to be resistant to the object falling through it and tend to "hold it up". I believe in a pure vacuum, even a feather and a Bowling ball would fall at the same rate and hit the ground together because there would be no resistance and equal gravity pulling on each.