Why does the heavier object hit the ground first when a book and a flat piece of paper are dropped together?

The reason the heavier object hits the ground first when a book and a flat piece of paper are dropped together is that the book is less affected by air resistance. In free fall, all objects experience gravitational pull towards the ground, but air resistance acts in the opposite direction. The flat piece of paper, due to its larger surface area relative to its weight, experiences significant air resistance, which slows its descent.

On the other hand, the book, being heavier and more compact, has a smaller surface area compared to its weight, which means that the effects of air resistance are negligible compared to the gravitational force acting on it. As a result, it accelerates towards the ground more quickly and reaches the ground before the flat piece of paper does.

Thus, in this scenario, the interaction between mass and surface area in relation to air resistance explains why the heavier object hits the ground first.