Tendon the Achilles tendon stretches as the ankle joint dorsiflexes. During the last portion of the stride, as the foot plantar-flexes (pointing the toes down), the stored elastic energy is released. Furthermore, because the tendon stretches, the muscle is able to function with less or even no change in length, allowing the muscle to generate greater force. The mechanical properties of the tendon are dependent on the collagen fiber diameter and orientation. The collagen fibrils are parallel to each other and closely packed, but show a wave-like appearance due to planar undulations, or crimps, on a scale of several micrometers. In
Elastic and inelastic collisions apparatus Elastic and inelastic collisions apparatus The elastic and inelastic collisions apparatus is a large apparatus to study elastic and inelastic collisions. It consists of a large frame carrying two beams from which two rows of six and two wooden balls, respectively, are suspended from pairs of strings. The instrument was often used with two elastic balls (of ivory) or inelastic balls (of wet clay), of equal or different mass. By changing the parameters of the experiments such as height of fall and mass, one could conduct a systematic investigation of collision-related phenomena. For example, when the row of balls is