Falling Slinky - Physics Demonstrations - Falling Slinky | Physics Undergraduate Labs

When standing on desks or tables, ensure the surface is stable and clear of obstacles. Use a step stool or ladder for access if needed. Avoid sudden movements that could cause loss of balance.

Purpose

When a suspended slinky is released, its bottom remains completely stationary until the collapsing top reaches it. This challenges the assumption that all parts of a falling object accelerate simultaneously and demonstrates that changes in tension propagate at finite speed through an extended body.

Side-by-side frames showing a hand holding a red plastic slinky suspended against a chalkboard (left) and the moment after release with the top collapsing while the bottom coils remain stationary (right)

Person in yellow shirt standing in front of a chalkboard, holding a large white plastic slinky extended from a raised hand down to floor level

Figure 1: Before and after release: the left frame shows the slinky held in equilibrium; the right frame shows the top collapsing downward while the bottom coils remain stationary.

Figure 2: Demonstrator holding the large plastic slinky fully extended before release. Stand on the desk for greater drop height and instruct students to watch the lowest coils.

Safety Warnings

Warning: Elevated Platform Safety

Purpose