Clumping by Surface Tension
This Demonstration shows the movement of two small, low-density floating objects, such as the doughnut-shaped Cheerios of the well-known oat cereal, toward each other due to the force of buoyancy. The strong buoyancy force makes a Cheerio float above the milk and the liquid's surface forms a meniscus that exhibits surface tension and acts as a flexible membrane. A Cheerio will seek the highest point of the membrane and thus will find its way to either another Cheerio or the wall of the container. Surface tension prevents the Cheerios from floating higher above the milk. In addition, cohesion and adhesion affect the milk's meniscus near the container wall. This clumping phenomenon is known as the Cheerios effect.
This was a project for Advanced Topics in Mathematics II, 2016–2017, Torrey Pines High School, San Diego, CA.
The forces , , and are buoyancy, surface tension, adhesion and cohesion, respectively.
 D. Vella and L. Mahadevan, "The 'Cheerios Effect,'" American Journal of Physics, 73(9), 2005 pp. 817–825. doi:10.1119/1.1898523.