From: A Statically Unstable Passive Hopper: Design Evolution Date of download: 11/7/2017 Copyright © ASME. All rights reserved. From: A Statically Unstable Passive Hopper: Design Evolution J. Mechanisms Robotics. 2017;9(1):011016-011016-7. doi:10.1115/1.4035222 Figure Legend: Ball and car toy. A toy car A is attached by a curved wire spring B to highly elastic rubber ball C. One end of the wirespring is embedded in the ball. The opposing end of the wire spring is attached by hinge D to the top of the toy car. The lower panel shows the approximate orientation of ball during one hop cycle, as the car leads the ball down the hill. Arrows indicate the alternating direction of ball pitching between collisions (multimedia extension 2 video).