Physical system What happens when you drop a book
Why does it fall on the floor
Why doesn't it rise higher in the air

this happens because there is gravitational force acting upon it.

The book will fall when you drop it and make a thud, It falls on the floor because there is no force holding it up, but there is a force pulling it down, the gravitational force. It doesnt rise higher in the air because It does have lighter like the properties of a balloon.

Explanation:

answer; equivalent to a one(1) horsepower motor;