In the 1850s, railways were used to move coal from one location to another using only the force of gravity and a hand-brake to slow down. By the 1870s, thrill-seekers recognized the potential fun in this gravity-driven contraption. Create a two-rail marble roller coaster. Plan the path of your marble. Embrace centripetal force to keep the marble on the track through a banked curve. Each creation is unique. Test your track and your friends.
