The science museum that I volunteer at recently opened up the traveling math exhibit that I’ve been looking forward to for a while. One of the activities features a piece of equipment that, as a physics student/teacher, is near and dear to my heart: the motion sensor. As you walk towards and away from the sensor, it records how far away you are and plots this distance on a graph.
It’s a nifty setup that gets people thinking about how motion can be described both visually and mathematically, but it does raise the question: how does the sensor know how far away you are?
The explanation is best illustrated with a game of catch.