66th Annual STS (2006-2007)
Finalists
Meredith Ann MacGregor

COLORADO
Meredith Ann MacGregor, 18, of Boulder, investigated the Brazil Nut Effect, a phenomenon in which shaken granular particles separate out by size with the largest on top, for her physics Intel Science Talent Search project. To test the fluid-like phenomena of these particles in her home basement laboratory, Meredith constructed containers of Lucite®, both rectangular and cylindrical, that could vibrate vertically. She filled each container with granular materials ranging in size from 0.5 mm glass beads to 3.0 mm tapioca pearls. She tracked the motion of a large "intruder" particle among smaller granules through computer modeling and experiments. She concluded that, although vibration-induced convection flow contributes to particle size separation, the effect of air flow through the granules when shaken is key to understanding this phenomenon. First in her class of 444 at Fairview High School, Meredith competes in varsity cross country and track, enjoys playing the violin and sailing. The daughter of Dr. Keith and Kathryn MacGregor, Meredith received an Intel Foundation Young Scientist Award at Intel ISEF in 2006 for her work in physics. She hopes to attend Harvard or Princeton.