In 1971 Apollo 15 astronaut David Scott performed a simple experiment. It was interesting because Astronaut Scott was standing on the surface of the Moon when he did it!
Your book shows (on page 50) a drawing of a feather and a coin falling through a vacuum inside a vacuum tube. (A vacuum is created by removing all the air from a container.) The photo on the same page shows a feather and an apple dropping through a vacuum. It's impossible to create a total vacuum on Earth, though. Astronaut Scott was on the Moon, which has no atmosphere. He was standing in the vacuum of space, which is nearly total. (Note that the Moon does have gravity. Gravity on the Moon is much less than gravity on the Earth. But things are pulled towards the surface of the Moon, just as they are on Earth.)
The movie below shows Astronaut Scott holding a hammer in his right hand, and a falcon feather in his left hand. He drops them at the same time. What happens? How is this different from what might happen in our lab?
"In my left hand I have a feather, and in my right, a hammer"
"One of the reasons we're here today is because of Galileo. He made an important discovery a long time ago"
"What would be a better place to confirm his findings than on the Moon?"
"We thought we'd try it here for you.
The feather is a falcon feather."
"I'll drop the two of them here."
"Hopefully, they'll hit the ground at the same time."
"How about that? Galileo was correct!"
You must have QuickTime installed on your computer to see this movie. You can download QuickTime for both Windows and Mac computers from http://www.apple.com/quicktime/products/qt/ .