First Place - Contrived Category

Title: Cohesion of America
Student: Tim Putnam
School: Buxmont Academy at Feasterville, Pipersville, PA
Teacher: Barbara Knupp

I set up a penny on a flat table and used a pipette to put small drops of water on the penny to show adhesion and cohesion. Adhesion is the force that holds the water to the penny. This is why the drops stay on the penny. From our perspective the penny seems smooth, but it is actually very rough. This causes the molecules to fit into the spaces, and it has more surface area because of the roughness and spaces. Cohesion is the force that holds water to water. That is why the water appears in droplets. The water molecules attract each other and are held in the drop shape. The adhesive and cohesive forces are counteracting the force of gravity. This allows the drops to stay on the sides without rolling off of the penny. Surface tension holds the water in a spherical shape from the cohesive pull of the molecules causing tension at the surface. The water is in a rounded shape to reduce surface area because of the tension. This is why the drops of water are rounded mounds rather than flat and spread out.