A trip to an amusement park is the setting for this introduction to the concept of centripetal force in terms of Newton's laws of motion and vector quantities.  A student who is a physics major helps his friend understand the action-reaction forces that cause a body to stick to the wall of the Gravitron ride as it spins.  The case intentionally avoids the use of mathematics so that students will not get bogged down in solving equations while trying to internalize complicated concepts.  Instead, this introduction to the concept of centripetal force is intended as a jumping off point for more detailed discussions of the underlying mathematics. The case is appropriate for use in lower division undergraduate college or senior high school classes. It has been used with students in introductory physics classes for science majors and in non-majors general physics classes. It could also serve as the basis for an informal writing assignment in a writing intensive course.