9781422282977

7

Science and Energy

INTRODUCTION Moving Along

Words to Understand drag  resistance experienced by an object that is moving through air or water friction  resistance experienced by an object when it rubs up against another object supersonic  faster than the speed of sound

W hether in a horse-drawn card, a wind-powered ship, or an electric car, transportation is central to our lives. Humans have always been interested in going from here to there safely, directly, and in the least amount of time. Some people such as Elon Musk, however, are not satisfied with thewaywe humans currently travel. In 2013,Musk,who has given the world the Tesla electric car and private spaceflights to the International Space Station, proposed a newmode of travel—the Hyperloop—that he hopes will revolutionize transportation just as steamships, automobiles, and airplanes did.