During a roller coaster ride, the body experiences acceleration in three dimensions. An accelerometer can measure and provide a graph of the forces on the body during different parts of a ride. To couple the experience of the body to pictures of the ride and an analysis of data can contribute to a deeper understanding of Newton's laws. This article considers the physics of launched roller coasters. Measurements were performed with a three-dimensional co-moving accelerometer. An analysis is presented of the forces in the different ride elements of the Kanonen in Goteborg and the Speed Monster in Oslo, which both include loops and offer rich examples of force and acceleration in all dimensions. (Contains 12 figures and 1 footnote.)