Book excerpt: You push a swing. Your brother pulls a wagon. Forces are at work all around you. But what exactly is a force? And how do forces act on 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 BooksTM collection. With high-energy designs, exciting photos, and fun text, Lightning Bolt BooksTM bring nonfiction topics to life!