Audisee(R) eBooks with Audio combine professional narration and text highlighting to engage reluctant readers! A ball drops to the ground. Leaves fall from a tree. Gravity is at work all around you. But what exactly is gravity? And how does it affect different objects? Read this book to find out! Learn all about matter, energy, and forces in the Exploring Physical Science series-part of the Lightning Bolt Books(TM) collection. With high-energy designs, exciting photos, and fun text, Lightning Bolt Books(TM) bring nonfiction topics to life!