Theme parks are big business. In the United States there are nearly 500 theme and amusement parks which generate over $10 billion a year in revenue. The theme park business is also growing in Europe and Asia. Rides are the main attraction at most parks, and at the center of this attention are the roller coasters. Engineers and designers compete to make them bigger and faster to increase park attendance. Roller coaster fans will wait in line for hours for a speedy, stomach-churning, head spinning 2-minute ride. What makes a roller coast fast