High School Photo Winner's Showcase

School: Glenbard West High School

Teacher: Nicholas Szarzak

In this photograph there is a picture of an Ambystoma laterale, the more common name for this amphibian is the Salamander. As it was carefully crawling over the submerged leaves, the water around it starts to slide up the abdomen and tail of the salamander. This natural phenomenon is known as cohesion and adhesion. The attractive forces of cohesion and adhesion act over a short range and vary in magnitude, depending on the substances concerned. If the salamander is fully submerged in water and then withdrawn, water will cling to it, showing that the force of adhesion between water and the salamander is greater than the force of cohesion between water molecules. The physics of adhesion allows the water to stick to something that is tilted towards the ground. As you can see some droplets of water beaded up on the salamanders head. Without this cohesion between the water molecules, and the adhesion between the water and the Salamander skin, the water would drip to the pond level much quicker. In addition, the adhesion creates a frictional force that slows down the time it takes for the water to fall back into the pond, or may even prevent it from falling at all. If the water does not fall from the Salamanders head the cohesive and adhesive forces are completely defying Newton's Law of Gravitation. Showing that the forces between the Salamander and the water, are stronger then the force of gravity acting on the water itself.