Doppler dart demo

During last summer at Barrington High School, I taught a course in a summer bridge program designed to prepare students for physics. As an element of the course, students were asked to design a quantitative lab relating to something they enjoyed doing outside of school. The project required students to collect data, observe the effects of changing one variable, and present their conclusions. One group of students chose to determine the best method for completing timed paintball target practice courses. They wanted to see how firing a paint gun while moving toward and away from the target would affect the time required to complete the course. To answer these questions they decided to employ two automatic 18-dart Nerf® guns and a skateboard. Two experiments were performed, one with the student firing the dart gun while riding the skateboard toward the target and one with him firing the dart gun while riding the skateboard away from the target (Fig. 1). (Note: Teachers should inform their school administrators of their intent to use toy guns in class.)