Here is where Galileo comes in. He carefully dropped balls from towers and rolled them down inclines. He stated that the reason your book drops faster than your paper is not due to their difference in mass, but rather because air resistance (friction) affects the falls differently.

Let's explore Galileo’s idea.

Step 1: Go to the moon where there is no air to affect the way things fall.

Step 2: Drop a feather and a hammer at the same time.

Oh, going to moon is not in your budget? Well, watch this video of an astronaut who tried it out in 1971: