Collision of Two Blocks in a Circular Tube
Two squares of different masses travel inside a thin horizontal circular tube. The red block starts at point E with speed three meters per second while the blue block is initially stationary at the collision point. Their motion and collisions are shown together with a synchronized velocity‑time graph in the upper right corner. After the first impact the speeds exchange, and after the second impact the blue block stops and the red block returns to the first collision point. The whole scene is slowed down four times to highlight the near‑instantaneous collisions.