Move a Little Closer by Shanique Shanalee Reid
Honorable - Contrived Category
School: Classical Magnet
Teacher: Thomas A. Holloway
Normally sand pours easily and can be pushed around with ease because there are large air gaps and the grains touch only lightly over small areas. However, with each stab of the wooden stick entering the sand, the grains are compressing causing them to pack more tightly together. The air gaps decrease in size and the sand grains rub against each other more. They cannot move as freely, and start to arrange in a pattern that does not change. The sand you could previously pour like a liquid becomes solid. The more grains of sand pressing on the wooden stick, and each one of those more tightly packed in, the friction between the stick and sand increase. If the friction force between the sand and stick equals the combined weight force of the sand and the plastic cup, then the balance of forces means the knife is held in place. The friction between the stick, sand and the walls of the plastic cup allow the jar to lift which is the effect of the increase of the friction inside the walls of the plastic cup and the sand.
