Which object hits the ground first when dropped from the same height: a book or a flat piece of paper?

When a book and a flat piece of paper are dropped from the same height, the book will hit the ground first due to its greater mass and more compact shape, which allows it to overcome air resistance more effectively than the flat piece of paper.

The flat piece of paper, because of its larger surface area relative to its mass, experiences more air resistance as it falls. This increased drag force acts against the force of gravity, slowing its descent. In contrast, the book, being denser and less affected by air resistance, accelerates downward more effectively under the influence of gravity.

This phenomenon can be observed better in a vacuum, where the absence of air resistance allows both objects to fall at the same rate and hit the ground simultaneously. However, in a real-world environment, the effects of air resistance favor the book, causing it to hit the ground before the flat piece of paper does.