Projects in High-Speed Photography
This series of images shows three stages in the collision of a BB with an elastic strip. It's easy to predict where the wishbone-shaped strip will snap.
The end that's closer to the impact site of the BB will be first to experience the force of the impact. In this case, that's the top.
The bottom of the strip is effectively held in place by its own inertia.
Eventually, all parts of the strip are moving forward, although at different speeds. Note that in the third photo, the upper portion of the strip has advanced past the captured BB. When the strip eventually comes to rest, the BB remains trapped, as the next image shows.
The photo is a composite of 3 collisions taken under similar conditions but with different time delays.