Anti-gravityHarvey LeiAward: Top 100
School: monta vista high school This photograph depicts a metal coil or spring that is in free fall, with the top moving downward in a blur, while the bottom of the spring stays still and clear, appearing to levitate. The spring was originally held vertically at rest by the top end of the coil so it would stretch naturally under the force of gravity. It was then released from rest and captured in this photograph. This phenomenon occurs because the spring originally hangs in equilibrium, where every section along its length experiences two main opposing forces. The gravitational force that acts downward at any point is balanced by an upwards spring force from the sections above that point. The moment the top of the spring is released, the force of gravity becomes the only significant force, so the top begins to fall. However, this loss of an upwards force is not immediately experienced by the lower sections of the spring, instead taking time to travel downwards as a propagating wave. Only when this wave reaches a coil do the forces become unbalanced, causing it to fall as well. Until that moment, each coil remains at rest as it did in equilibrium, with the same upward spring force. This results in the bottom of the spring appearing to levitate. Despite this, the center of mass of the spring still undergoes free fall like a rigid object. What makes this phenomenon interesting is not just this result but also the simplicity to both create and explain it. 
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